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Keywords:

  • late discriminative negativity;
  • mismatch negativity;
  • musical development;
  • P3a;
  • Singing

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

The relation between informal musical activities at home and electrophysiological indices of neural auditory change detection was investigated in 2–3-year-old children. Auditory event-related potentials were recorded in a multi-feature paradigm that included frequency, duration, intensity, direction, gap deviants and attention-catching novel sounds. Correlations were calculated between these responses and the amount of musical activity at home (i.e. musical play by the child and parental singing) reported by the parents. A higher overall amount of informal musical activity was associated with larger P3as elicited by the gap and duration deviants, and smaller late discriminative negativity responses elicited by all deviant types. Furthermore, more musical activities were linked to smaller P3as elicited by the novel sounds, whereas more paternal singing was associated with smaller reorienting negativity responses to these sounds. These results imply heightened sensitivity to temporal acoustic changes, more mature auditory change detection, and less distractibility in children with more informal musical activities in their home environment. Our results highlight the significance of informal musical experiences in enhancing the development of highly important auditory abilities in early childhood.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

In recent years, important advances have been made in demonstrating fast neuroplastic effects of formal musical training in childhood (Hyde et al., 2009; Meyer et al., 2011). For the majority of children, however, musical experience does not predominantly involve formal training on a musical instrument but mainly consists of informal musical activities such as singing and musical play at home. Little is known about how differences in such musical experiences are related to children's neural auditory discrimination skills.

It is evident that young children are well equipped to benefit from a musically enriched home environment. Behavioural and neuroscientific evidence plainly show that even young children possess the necessary auditory capabilities for perceiving music and display great interest in it (Trehub, 2003; Trainor, 2012). Furthermore, multiple lines of evidence indicate that the brain has a considerable capacity for neuroplastic changes in childhood (Trainor, 2005) and therefore might very well be shaped even by informal exposure to sounds. Also, the finding that the auditory system tunes to the culturally typical linguistic (Kuhl, 2004) and musical (Hannon & Trainor, 2007) sounds in childhood without specific training shows that the brain is shaped by everyday auditory experience.

Singing is probably the most common musical behaviour that parents and children engage in together, and therefore parental singing is arguably the most typical form of ‘live music’ that young children hear. Children themselves also actively engage in various musical behaviours such as singing and moving to music. Given the malleability of the young brain, it seems quite plausible that parental singing and musical play by the child influence the development of the auditory system.

The mismatch negativity (MMN), P3a, late discriminative negativity (LDN), and reorienting negativity (RON) of the event-related potentials (ERPs) provide a method for investigating auditory change detection and attention in young children at the neural level. The MMN is an index of memory-based detection of auditory change (Näätänen, 2001), whereas the P3a reflects attention shift towards surprising auditory events (Escera et al., 1998). These responses are used widely as indicators of the accuracy of neural auditory discrimination (MMN) and the sensitivity of involuntary attention allocation (P3a). In children, the MMN and P3a are often followed by the LDN, a component for which multiple functional roles have been proposed (see 'Discussion'). The LDN is usually not seen in adults and therefore its presence may indicate immature processing of auditory changes. Finally, the RON reflects the reorienting of attention after a distracting auditory event (Schröger & Wolff, 1998).

The current study explored the relation between informal musical activities at home and the aforementioned electrophysiological indices of auditory discrimination and attention. ERPs were recorded to different types of auditory changes in the multi-feature paradigm (Näätänen et al., 2004). It was hypothesized that a musically enriched home environment would be associated with heightened sensitivity to auditory changes reflected by augmented MMN and P3a responses to deviant tones, more mature later processing of auditory changes reflected by decreased LDN, and lower distractibility by salient, surprising auditory events reflected by smaller P3a and RON to novel sounds.

Materials and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Participants

Thirty-one children participated in the experiment. The data from six subjects were discarded from the analysis either because there were < 60% of artifact-free trials (n = 4) or because of incomplete questionnaire data (n = 2). The mean age of the remaining 25 subjects (13 females) was 2.79 years (range 2.38–3.29 years). The ERP data of 13 subjects were reported earlier in Putkinen et al. (2012). Signed informed consent was obtained from the parents for their child's participation in the experiment. The child's consent was obtained verbally. The experiment protocol was approved by the Ethical Committee of the former Department of Psychology, University of Helsinki, Finland.

The participants had Finnish as their native language and were from families with two parents and one to three children. For 18 of the families, at least one parent had either a bachelor's (or equivalent), master's, or doctoral degree and for the majority of the families their monthly income was at or above the Finnish average level. The parents were asked about their child's possible hearing difficulties and other illnesses. The parents also provided the child's health summary, which contained information from the child's regular visits to a nurse and/or medical doctor that had occurred at least three times per year. Except for allergies, atopic skin or asthma, the subjects had no illnesses and no reported hearing or other medical problems. The children were born at full term, had normal birth weights, and their weight and height had developed normally.

All of the children also had some musical experience outside the home as they had all attended the same playschool involving musical activities. The playschool sessions took place on a weekly basis expect for the summer months and national holidays (max. approximately 30 sessions/year). In the playschool, the emphasis was on the enjoyment of playful musical group activities such as singing in group, rhyming, and moving with the music, etc. and not on a formal music-educational program involving training on musical instruments. According to the parents, all the children had attended the playschool regularly and displayed great interest in the playschool activities. One of the parents always accompanied the children in the playschool.

Stimuli and procedure

During the experiment, the children sat in a recliner chair either on a parent's lap, or by themselves while the parent sat on a chair next to them in an acoustically attenuated and electrically shielded room. The children and their parents were instructed to move as little as possible and to silently concentrate on a self-selected book and/or children's DVD (with the volume turned off) during the experiment. Generally, the children were able to comply with these instructions well although all children talked and switched their position at least a few times during the recordings. The subjects were video-monitored throughout the 50 min experiment.

The multi-feature paradigm (Näätänen et al., 2004; Putkinen et al., 2012) was used in the experiment. In the paradigm, deviant tones (probability = 0.42) from five categories and novel sounds (probability = 0.08) alternated with standard tones (probability = 0.50). The order of the deviant tones and novel sounds was pseudo-random (with the restriction that two successive non-standard sounds were never from the same category).

The stimulus sequence included 1875 standard tones, 1590 deviant tones, and 280 novel sounds. The sounds were presented with a stimulus onset asynchrony of 800 ms. The first six tones of the block were standard tones out of which the first five were excluded from the analysis. The stimuli were presented through two loudspeakers in front of the participant at a distance of 1.5 m and at an angle of 45° to the right and left.

The standard and deviant tones included the first two upper partials of the fundamental frequency. Compared with the fundamental, the intensity of the second and third partials were −3 and −6 dB, respectively.

The standard tones had a fundamental frequency of 500 Hz, were 200 ms in duration (including 10 ms rise and 20 ms fall times), and were presented at an intensity of 80 dB (sound pressure level) via both loudspeakers.

Each deviant tone differed from the standard tones in frequency, intensity, duration, sound-source location, or by having a silent gap in the middle, but otherwise they were identical to the standard tones. The frequency deviants included large (f0: 750 or 333.3 Hz), medium (f0: 400 or 625 Hz) and small (f0: 454.5 or 550 Hz) frequency increments and decrements. The duration deviants included large, medium and small duration decrements, which were 100, 150, and 175 ms in duration, respectively. Only the responses to the largest frequency and duration deviants were included in the analysis because of their better signal-to-noise ratio compared with the responses to the smaller deviants. The gap deviant had a 5 ms silent gap (5 ms fall and rise times) in the middle of the sound. The intensity deviants were either −6 or +6 dB compared with the standard. Finally, the sound-source location deviants were delivered through either only the left or right speaker (no intensity compensation was employed). The large frequency and duration deviants were both presented 140 times and the intensity, sound-source location, and gap deviants, in turn, were presented 250 times each.

In addition, repeating and varying novel sounds were included in the sequence. Similarly to the standard tones, the novel sounds were 200 ms in duration and their mean intensity was 80 dB. The varying novel sounds were machine sounds, animal calls, etc., whereas the repeating novel sound was the word /nenä/ (‘nose’ in Finnish), spoken in a neutral female voice. The repeating and varying novel sounds were presented 216 and 72 times, respectively. Unlike the repeating novel sounds, each individual varying novel sound was presented no more than four times during the whole experiment. Furthermore, one-third of the varying novel sounds were presented via the right, one-third via the left, and one-third via both loudspeakers, whereas the repeating novel sounds were always presented through both loudspeakers. Because of these factors, the varying novel sounds are arguably more likely to trigger cognitive processes related to novelty detection and distraction than the repeating novel sounds. Consequently, only the responses to the varying novel sounds were included in the analysis of the current study.

The parents of the children filled out a detailed questionnaire concerning the musical behaviour of their children and their own musical activities at home. With regard to singing, both parents were asked to report (i) how often they sang to their children, and more specifically (ii) how often this involved singing familiar songs (e.g. well-known children's songs) or (iii) songs they had invented themselves. With regard to the musical behaviours of the children at home, the parents rated (i) how often their children sang familiar melodies, (ii) sang self-invented melodies, (iii) drummed rhythms, or (iv) danced at home. For all the aforementioned questions, the answers were given using a five-point scale (1, almost never; 2, once a month at most; 3, several times a month; 4, approximately once a week; 5, almost daily).

The scores for the questions related to singing were added together to form a composite singing score separately for both parents. Similarly, the scores for the questions regarding the musical behaviour of the children were summed to form a composite musical behaviour score for each child. Finally, these composite scores were normalized by subtracting the mean of the variable from each score and dividing this difference by the SD of the variable (hence, scores below the mean are negative). The normalized musical behaviour scores and father's singing scores were added together to form an overall composite score for musical activities at home. In line with previously reported differences in the prevalence of maternal and paternal singing (Trehub et al., 1997), the overwhelming majority of the mothers responded with the highest possible value to all the questions related to child-directed singing. In contrast, there was considerable variation in the amount of singing reported by the fathers. Therefore, for the questions regarding child-directed singing, only the fathers' scores were included in the analysis.

Electroencephalographic recording and data analysis

The electroencephalogram (band pass during recording 0.10–70 Hz, 24 dB per octave roll off, 500 Hz sampling rate) was recorded (NeuroScan 4.3) from the channels F3, F4, C3, C4, Pz, and the left and right mastoids using Ag/AgCl electrodes with a common reference electrode placed at Fpz. The electro-oculogram was recorded with electrodes placed above and at the outer canthus of the right eye. At the beginning of the measurement, the impedance of the electrodes was lower than 10 kΩ.

The data were filtered offline between 0.5 and 20 Hz electroencephalographic epochs from 100 ms before to 800 ms after tone onset and were baseline corrected against the 100 ms prestimulus interval. Epochs with a voltage exceeding ± 100 μV at any channel were discarded. After averaging the remaining epochs separately for each stimulus and subject, the resulting ERPs were re-referenced to the average of the two mastoids. Grand-average responses were formed by averaging the individual ERPs separately for each deviant type, novel sounds and the standards. Difference signals were computed by subtracting the responses elicited by the standard tone from the responses elicited by each deviant tone and the novel sounds.

The peak latencies of the responses were determined from the deviant/novel-standard difference signals from channel F3, which was deemed to be a representative of the response for all four channels included in the analysis. For the deviant tones, the peak latency for the MMN was defined as the latency of the largest negativity between 200 and 300 ms, for the P3a as the latency of the largest positivity between 200 and 300 ms, and for the LDN as the latency of the largest negativity between 500 and 600 ms after the deviant became physically distinct from the standard. For the novel sounds, in turn, the peak latency of the P3a was determined as the latency of the largest positivity between 200 and 300 ms and for the LDN/RON as the latency of the largest negativity between 600 and 700 ms.

For the analysis of the MMN and P3a, mean amplitudes of the responses were calculated on channels F3, F4, C3 and C4 over 50 ms time windows centred on the peak latencies. These values were then averaged together separately for each response and the average value was used for testing the significance of the response and for the correlation analyses. An identical procedure was used for the LDN and novelty P3a except that a 100 ms time window was used in the analyses as these responses spanned a longer time period than the MMN and the P3a elicited by the deviant tones.

To test the statistical significance of the MMN, P3a and the LDN for a given deviant, the mean amplitudes were compared with zero with a two-tailed one-sample t-test. Pearson's correlation coefficients between the overall musical behaviour score and the MMN, P3a, and LDN amplitudes were calculated. Partial correlations between the response amplitudes and the overall musical activities at home score were also calculated to control for various external factors. These factors included the child's age, gender, and socioeconomic status. The socioeconomic status measure included the income and education of both parents measured on six-step scales (income scale: 1, under 1000 Euros/month; 2, 1000–2000 Euros/month; 3, 2000–3000 Euros/month; 4, 3000–4000 Euros/month; 5, 4000–5000 Euros/month; 6, over 5000 Euros/month; education scale: 1, comprehensive school; 2, upper secondary school or vocational school; 3, a higher degree than upper secondary school or vocational school that is not a bachelor's, master's, licenciate, or doctoral degree; 4, bachelor's degree or equivalent; 5, master's degree or equivalent; 6, licenciate or doctoral level degree). The answers of both parents to these questions (i.e. number from one to six) were added together to form a composite socioeconomic status score for the parents of each child.

Exposure to recorded music at home was not included in the musical activities index because it was expected that the more active and interactive musical behaviours would be more likely to be associated with auditory development in 2–3-year-olds (cf. Gerry et al., 2012). The number of hours per week that the parents listened to music from CDs, DVDs, radio etc. with their children was nevertheless included as a control variable in the partial correlations to highlight that the correlations between the measures of main interest were not mediated by this variable. For this particular factor, either the mother's or father's response was missing for five children and was substituted by response median. The duration of the playschool attendance (average 17 months; range 1–30 months) was also included as a control variable. It should be noted that neither the exposure to recorded music nor the duration of the playschool attendance correlated with the response amplitudes or the measures included in the musical activities index with the traditional 0.05 criterion. For all of the control variables, however, the P-value for the correlation with either one or more of the responses or the musical activities index was lower than 0.20, which justifies the inclusion of these factors in the statistical model (Maldonado & Greenland, 1993) despite the reduction in parsimony. As a further control, two-way independent samples t-tests were conducted to compare the response amplitudes and the composite musical activities scores of the children whose parents (one or both) were active musicians (N = 10) with those of the rest of the children. These preliminary analyses revealed no evidence for differences in response amplitudes between these groups: musical activities at home score: t23 = 0.06, = 0.95; duration: MMN t23 = 1.82, = 0.081, P3a t23 = −1.00, = 0.326, LDN t23 = −0.345, = 0.733; gap: MMN t23 = 1.05, = 0.306, P3a t23 = −0.793, = 0.436, LDN t23 = −0.484, = 0.633; frequency: LDN t23 = −0.504, = 0.619; intensity: LDN t23 = 1.55, = 0.136; location: LDN t23 = −0.390, = 0.700; and novel sounds: P3a t23 = −1.23, = 0.212, RON t23 = 0.125, = 0.902.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

Responses to deviant tones

The duration and gap deviants elicited significant MMN-like responses followed by significant P3a-like and LDN-like responses (see Fig. 1A and B, and Table 1). In contrast, the grand-average difference signals of the frequency, intensity, and location deviants were dominated by prominent LDN-like deflections (see Fig. 1C–E and Table 1). The amplitudes of the MMN-like responses to the duration and gap deviants did not correlate with the overall musical activities score. Separate analyses for the child's musical behaviour score and the singing score did not reveal significant correlations with the MMN amplitudes either. In contrast, the amplitudes of the P3a to the duration and gap deviants, and LDNs to all deviant types were positively correlated with the overall musical activities score, i.e. larger scores were associated with larger P3a and lower LDN amplitudes and vice versa. All of these correlations remained significant after controlling for age, gender, socioeconomic status, the number of weekly hours of listening to recorded music, and the duration of playschool attendance (see Table 1).

Table 1. The mean amplitudes and peak latencies of the responses to the deviant tones and the t-values for the mean amplitudes
DeviantResponseAmplitudeLatency t (24) Cohen's d r r 2 Partial r
  1. a

    < .05.

  2. b

    < .01.

  3. c

    < .001.

  4. Pearson's correlation coefficients between the response mean amplitudes and the musical activities score and the corresponding r-squared values are listed in columns r and r2, respectively. The rightmost column lists the partial correlations controlling for the child's age, gender, SES, the number of hours the parents listened to recorded music with their children, and the duration of the children's attendance at the playschool.

DurationMMN−3.2326−7.12c2.91ns ns
P3a1.714642.49a1.020.46a0.210.48a
LDN−2.96652−5.06c2.070.46a0.210.66b
GapMMN−3.31326−6.07c2.48ns ns
P3a1.54502.20a0.900.69c0.480.69b
LDN−4.03652−8.10c3.310.50a0.250.69b
FrequencyLDN−4.60588−7.50c3.060.56b0.310.59b
IntensityLDN−1.71598−4.00b1.630.48a0.230.47a
LocationLDN−2.05536−5.13c2.090.60b0.380.72b
image

Figure 1. (A–E) Difference signals for the deviant sounds and the scatter plots illustrating the correlations between the P3a (diamonds) and LDN (dots) amplitudes and the musical activities at home composite score. In the ERP figures, the thin dashed lines are the responses at the channels F3, F4, C3, and C4 and the thick solid line is the average of the signals at these channels. The grey bars indicate the latency windows from which the response mean amplitudes were calculated. *P < 0.05, **P < 0.01, ***P < 0.001.

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Responses to the novel sounds

The novel sounds elicited a significant novelty P3a-like response peaking at 252 ms [t(24) = 10.53, < 0.001] followed by an LDN/RON response peaking at 676 ms [t(24) = −12.41, < 0.001] (see Fig. 2). The LDN/RON amplitude correlated positively with the overall score for musical activities at home (= 0.41, < 0.05), whereas no significant correlation was found between the musical activities score and the novelty P3a amplitude. The correlation between the LDN/RON amplitude and the overall score for musical activities at home remained significant after controlling for age, gender, socioeconomic status, the number of weekly hours of listening to recorded music, and the duration of playschool attendance (= 0.55, < 0.05). However, when the musical behaviour score and the singing scores were examined separately, a significant negative correlation (= −0.48, < 0.05) was found between the P3a amplitude and the singing score, i.e. smaller singing scores were associated with larger novelty P3as and vice versa. This correlation also remained significant after controlling for the factors listed above (= −0.53, < 0.05). No correlation was found between the P3a and RON.

image

Figure 2. The difference signal for the novel sounds and scatter plots illustrating the correlations between P3a amplitude and the singing score (left scatter plot) and between RON amplitude and the musical activities at home composite score (right scatter plot). In the ERP figure, the thin dashed lines are the responses at the channels F3, F4, C3, and C4 and the thick solid line is the average of the signals at these channels. *P < 0.05.

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Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

The current study examined the relation between informal musical activities at home (e.g. singing, dancing) and neural sound discrimination skills reflected by the MMN, P3a, LDN, and RON responses in 2–3-year-old children. The P3a-like response elicited by the duration and gap deviants and the LDN elicited by all deviant types correlated positively with the overall amount of informal musical activities. The larger P3a-like responses to the gap and duration deviants in the children with high overall scores for musical activities at home imply that these children have a lowered threshold for attention allocation towards subtle temporal changes in sound. The reduced amplitude of their LDNs across all of the deviant types may indicate that the later processing of various types of acoustic changes is more mature in these children compared with those from less musically active homes. Furthermore, the P3a and RON elicited by the novel sounds correlated with paternal singing and the overall amount of informal musical activities, respectively. The reduced P3as and RONs to the novel sounds in the children from more musically active homes indicate that musical activities are associated with lowered distractibility. Therefore, the findings suggest that informal musical experience might facilitate or speed up the development of highly important auditory functions in early childhood.

The mismatch negativity-like responses

It is commonly asserted that the MMN is relatively adult-like in its morphology early in development (Cheour et al., 2001; Trainor, 2012). Indeed, a wide variety of deviant stimuli elicit MMN-like responses in infants under the age of 6 months (Trainor, 2012). Further, some studies indicate that the MMN only slightly reduces in amplitude and latency between preschool age and adulthood (Gomot et al., 2000; Shafer et al., 2000). In the current study, however, only the duration and gap deviants elicited prominent MMN-like responses, whereas the other deviant types did not (see also Putkinen et al., 2012). Other studies have also failed to obtain MMNs to frequency (Gomes et al., 2000; Morr et al., 2002) and intensity (Sussman & Steinschneider, 2011) deviants in passive odd-ball setting even in children who were older than those participating in the current study [note, however, that in the study of Sussman & Steinschneider (2011) a frequency MMN was obtained]. Therefore, the MMN appears to be less robust in children than in adults and its maturational time-course might vary between different auditory features.

Auditory experience is known to influence the MMN in childhood and therefore it was expected that the MMN amplitude would correlate with the overall score for musical activities at home. However, no such correlation was found. The evidence for experience-dependent plasticity on the MMN mainly comes from studies that, unlike the current one, centre on the influence of the language environment (e.g. Cheour et al., 2002) or the effects of intense formal musical training in school-aged children on auditory discrimination (Chobert et al., 2011; Meyer et al., 2011; Virtala et al., 2012). The current study indicates tentatively that, in contrast to these types of auditory experiences, the MMN might not be sensitive to differences in the kinds of informal musical experience examined in the current study at least in 2–3-year-olds.

The P3a-like responses

As was the case with the MMN, the duration and gap deviants were also the only ones out of the five deviant types that elicited a P3a-like response. Unlike the MMN, however, these responses were correlated with the overall musical activities at home score. Interestingly, contrasting results were obtained with regard to the P3as elicited by the deviant tones and novel sounds. Namely, the musical activities at home were associated with augmented P3a responses to the deviant tones but a reduced P3a to the novel sounds.

At least in the current experimental setting, a P3a-like response to the deviant tones might reflect the sensitivity to fine variation in the auditory environment, whereas the novel-sound P3a might be related to distractibility by salient auditory changes. Evidence from various sources supports the intuitive idea that, in the sense just outlined, the P3a responses to subtle vs. pronounced auditory changes might reflect different aspects of attention allocation. Firstly, short-term auditory training has been found to enhance the P3a elicited by different types of subtle auditory changes (Atienza et al., 2004; Uther et al., 2006) and augmented P3as to difficult-to-detect deviants are seen in subjects with highly accurate auditory abilities such as musicians (e.g. Vuust et al., 2009). However, the P3a elicited by salient novel sounds that are well above the discrimination threshold is related to behavioural indices of distraction in childhood (Gumenyuk et al., 2004) and the novel-sound P3a has been found to be enlarged in highly distractible children such as those with attention deficit hyperactivity disorder (van Mourik et al., 2007) and major depression (Lepistö et al., 2004). In sum, a large P3a to subtle deviants appears to be associated with highly accurate auditory discrimination, whereas high-amplitude P3as to novel sounds may be indicative of heightened distractibility.

The P3a responses elicited by novel sounds vs. more subtle deviant tones might also display distinct developmental trajectories. For frequency deviants, an age-related increase in P3a amplitude has been reported (Wetzel & Schröger, 2007a). Admittedly, very few studies have specifically examined the development of the deviant elicited P3a. By visual inspection of the figures, a few studies (Gomot et al., 2000; Shafer et al., 2000; Horváth et al., 2009a) appear to support an age-related increase in the deviant-tone P3a but unfortunately these studies did not statistically examine the age differences in this response. In contrast, the novel-sound P3a seems to decrease (over the frontal electrodes) between preschool age and adulthood (Määttä et al., 2005; Wetzel & Schröger, 2007b; Wetzel et al., 2011), which might be related the maturation of the frontal cortex. Therefore, the enlarged P3as to deviants and reduced P3as to novel sounds found in the children from more musically active homes could be speculated to reflect more mature response morphology.

With regard to the novel-sound P3a, the correlation was specific to parental singing, whereas the correlation between this response and the overall musical activities at home score did not reach significance. This result indicates that, in particular, listening to informal musical performances (as opposed to more active musical play) is associated with reduced distractibility. Parental singing is highly effective in maintaining the attention of young infants (Trehub, 2009). In fact, singing by the father might be especially engaging for infants as indicated by behavioural measures of visual attention during listening to paternal vs. maternal singing (O'Neill et al., 2001).

Several authors have proposed that formal musical training might enhance executive functions (Moreno et al., 2011; Bialystok & DePape, 2009; Dege et al., 2011; however, see Schellenberg, 2011) such as selective attention (Trainor et al., 2009; Moreno et al., 2009). A recent longitudinal intervention study found support for these claims (Moreno et al., 2011). Our results indicate that even informal musical activity may also enhance functions related to auditory attention in childhood.

The late discriminative negativity and reorienting negativity responses

Although a number of suggestions for the functional significance of the LDN have been put forward, the cognitive processes underlying this response remain to be disambiguated. The two most common interpretations for the LDN are that it reflects either (i) the reorienting of attention after a distracting sound (Shestakova et al., 2003; Wetzel et al., 2006) similarly to the adult RON response or (ii) further assessment of auditory changes at a higher-order, cognitive level that follows the initial change detection reflected by the MMN (Čeponienė et al., 2004; Horváth et al., 2009a). These suggestions are not necessarily mutually exclusive as deviant sounds probably elicit multiple temporally overlapping but functionally distinct components in the LDN time range that are differentially activated depending on the stimuli and task.

Even the relatively moderate deviant stimuli used in the current study elicited LDN-like responses. For the frequency, intensity, and location deviants, the LDN was not preceded by a P3a. Therefore, the deviant LDNs were probably not related to distraction contradicting the attentional reorienting interpretation. However, if the LDN indeed reflects higher-order evaluation of auditory changes (Čeponienė et al., 2004), our results imply that this kind of processing is less pronounced in the children with high scores in the musical activities index. This suggests more economical use of these putative processing resources in children with more informal musical activities in their home environment.

Irrespective of its functional role, however, it is evident that the LDN elicited by deviant tones in a passive condition diminishes in the course of brain development (Mueller et al., 2008; Bishop et al., 2011) to the extent that it is not usually seen in adults (Cheour et al., 2001). This indicates that the LDN is typical for immature processing of auditory changes. The current study shows that, in 2–3-year-olds, rich informal everyday musical experience is associated with reduced LDN and therefore links such musical experience to more mature processing of auditory changes. It is noteworthy that this association was not limited to specific deviant types but was seen across all of the change types employed.

The late negativity elicited by the novel sounds was also significantly correlated with the overall score for musical activities at home. As the acoustically salient novel sounds are likely to cause distraction (Escera et al., 1998), the attention interpretation seems more plausible here than for the LDNs elicited by the relatively subtle deviants. Therefore, this response was termed as RON according to the adult response (Schröger & Wolff, 1998). Presumably, the children's attention was involuntarily drawn to the novel sounds after which the children reoriented their attention towards the primary task (i.e. watching a movie) and therefore the RON was elicited. It should be noted, however, that the relation of the RON-like component reported here and the adult RON response is uncertain especially as the young age of the subjects precluded the use of behavioural measures of distraction. However, based on previous studies it seems likely that processes related to attention allocation contributed to this component. For example, Gumenyuk et al. (2004) found that in school-aged children the reaction time in a visual task and the amplitude of a late negativity elicited by concurrently presented task-irrelevant novel sounds correlated positively (i.e. the longer the reaction times, the larger the RON responses), indicating that the late negativities elicited by novel sounds are also related to the amount of behavioural distraction caused by the unexpected sound in children. The current study shows that, in addition to novel-sound-elicited P3a, musical home activities are also associated with the reduction in this index of distractibility.

Do informal musical activities shape children's auditory processing?

It cannot be conclusively disentangled from correlational data whether the relation between musical activities and the P3a and LDN/RON responses found in the current study is due to changes directly caused by such activities in the neural mechanism underlying these responses. For instance, children who are (perhaps inherently) more accurate at detecting acoustic changes may be more predisposed to musical play and with their own behaviour encourage their parents to sing to them.

However, regardless of the initial impetus that eventually led to the observed relationships, it stands to reason that functional changes induced by musical activities could be a contributing factor. Firstly, although the auditory system remains malleable by experience throughout the life span, converging evidence from research on a variety of topics, such as the development of auditory processing after fitting of a cochlear implant (Eggermont & Ponton, 2003), the neural underpinnings of second language learning (Kuhl, 2004), and the effects of early blindness on cortical reorganization (Kujala et al., 2000), indicate that the auditory system exhibits a high potential for functional plasticity in childhood. Furthermore, the animal literature indicates that an acoustically enriched environment leads to functional changes in auditory cortical areas especially in young animals (Zhang et al., 2001; Engineer et al., 2004). Recent longitudinal studies have provided convincing evidence that formal musical training can lead to functional and structural changes in the brain in childhood (Hyde et al., 2009; Moreno et al., 2009; Gerry et al., 2012). In addition, studies on the tuning of the auditory system to culturally typical features of speech and music indicate that the auditory system shows long-term changes as a result of informal everyday exposure to sounds (Näätänen, 2001; Hannon & Trainor, 2007; Wong et al., 2011) and, further, that these changes may be specific to the most relevant deviance types/acoustic changes in speech vs. music (Tervaniemi et al., 2006, 2009). Although longitudinal studies are needed to conclusively resolve this issue, it seems reasonable that even informal musical experience in the form of musical play and parental singing might affect the responsiveness of the auditory system to acoustic changes. The causal relationships between these factors, however, are most likely multi-directional.

The influence of external factors

The issue of music specificity of the observed associations deserves careful consideration. We made an effort to control a number of external variables that might have influenced the observed correlations. The socioeconomic factors of parents' education and income, which are known to be associated with brain development (Hackmann & Farah, 2009), were statistically controlled for, as well as the age and gender of the children, and thus cannot explain the observed correlations. Furthermore, only a few children had hobbies or guided activities in addition to the playschool. Therefore, it is highly unlikely that the associations found in the current study were related to the overall number of hobbies of the children.

With regard to music-related external variables, it is important to note that as the children attended the same playschool and none of them had any additional formal musical activities they were matched with respect to the musical activities outside the home. Also, all correlations remained significant when the duration of the playschool attendance and the number of hours spent listening to recorded music were controlled for. Importantly, neither of these factors correlated with the musical activities index or the response amplitudes. Finally, we found no evidence that the responses of children whose parents were active musicians differed from the responses of children with non-musician parents. In sum, musical activities outside the home, the amount of exposure to recorded music, or the musical background of the parents cannot explain the associations between the musical activities at home and the P3a and LDN/RON amplitudes found in the current study.

Participating in guided musical activities outside the home is quite typical for Finnish children and such activities are offered widely in Finnish kindergartens. Therefore, our subjects do not dramatically differ from the Finnish norm in this regard. It could be nevertheless argued that the results might not be fully generalizable to children who have no musical activities outside the home. Children taking formal music lessons do indeed differ from children without musical training with regard to their perceptual abilities and various cognitive skills (Schellenberg, 2011), which might arguably influence how informal musical activities impact the brain. Still, it should be noted that the musical activities in the playschool were of low intensity and concentrated on enjoyment of musical group activities rather than on specific music-educational goals and cannot be equated with individualized formal training on a musical instrument. Furthermore, the finding that the duration of the playschool attendance was not associated with any of the neurophysiological or questionnaire measures speaks against the suggestion that the associations between the response amplitudes and musical behaviours were modulated by the playschool activities.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

The results of the current study are in line with the notion that everyday musical activities have beneficial effects on the development of sensitivity to auditory changes as measured by electrophysiological methods. Informal musical activities appear to enhance these auditory processes in early childhood and therefore might very well also influence the later development of auditory skills relevant not only for music perception but also speech processing. Our results highlight that not only formal musical training but also implicit musical learning may have important effects on auditory development. Future studies should look for factors that might mediate the relations between the musical activities and auditory skills revealed in the current study and map the long-term stability of these associations.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References

This work was supported by the National Doctoral Programme of Psychology. The authors have no conflict of interest to declare.

Abbreviations
ERP

event-related potential

LDN

late discriminative negativity

MMN

mismatch negativity

RON

reorienting negativity

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Conclusions
  8. Acknowledgements
  9. References