Audiol. Res., Volume 4, Issue 1 (February 2014) – 11 articles

This study describes the epidemiology of infants’ hearing loss (IHL) among patients under 3 months of age at Caritas Baby Hospital, the only pediatric hospital in Palestine. It was aimed to demonstrate that IHL is a major health problem in Palestine and to assess the first available data of the newborn hearing screening program conducted between September 25, 2006 and December 31, 2011. Data was uploaded and analyzed using Microsoft Excel and the Statistical Package for the Social Sciences software (SPSS version 21). A total of 8144 infants were tested, 4812 (59%) were males and 3332 (41%) were females. As to their origin, 72% (5886) came from the Bethlehem district, 25% (2044) from the Hebron district, while 3% (214) from the other Palestinian districts (Jericho, Ramallah, Nablus, Jenin and Jerusalem). The transient evoked otoacoustic emissions (TEOAEs) and the automated auditory brainstem response were used according to the manufacturer guidelines. The results were interpreted according to the indications of the American Academy of Pediatrics, the National Institutes of Health, and the European Consensus Development Conference on Neonatal Hearing Screening. Out of the 8144 infants tested, 1507 (14.6%) did not pass the 1^st test, 477 (32.8%) of these 1507 infants failed retesting, while 498 (33%) patients were lost to follow-up. Only 152 (31.9%) patients that failed retesting went to an audiologist. The audiologist evaluation revealed that 101 (66.4%) patients presented with a mild-moderate or profound hearing loss according to the Bureau International of Audiophonologie standards, 44 (28.9%) patients had otitis media, whereas 7 cases (4.7%) had no hearing disorders. The overall unadjusted percentage of hearing loss was 1.24%, and the adjusted overall percentage was 1.85%. The chart review showed that jaundice, sepsis, prematurity, lung disease were more common among the affected patients. The high prevalence of childhood deafness in Palestine is of utmost importance and deserves immediate attention on the part of the Palestinian government. Meanwhile, Caritas Baby Hospital undertook to set up a newborn hearing screening unit utilizing the TEOAE method. Full article

The aim of the study was to assess the effect of short-term perceptual training of music on some psycho-acoustical measures. The study was carried out in three phases. In first the phase pre-training evaluation was done which included raga identification and various psycho acoustical tests. Psycho-acoustical tests included measurement of differential limen of frequency and intensity, duration discrimination, gap detection, modulation detection, backward masking and duration pattern test. In the second phase, auditory perceptual training was given for raga identification and in the third phase post- training evaluation was done though same tests as mentioned in pre-training phase. A total of 10 normal hearing adults (7 males, 3 females) in the age range of 18-25 years participated in the study. The results revealed that all the subjects performed significantly better on raga identification after training. However; there was no significant difference in psycho-acoustical measures in pre and post-training. Full article

The aim of the present study was to evaluate the use of the envelope difference index (EDI) and log-likelihood ratio (LLR) to quantify the independent and interactive effects of wide dynamic range compression, digital noise reduction and directionality, and to carry out selfrated quality measures. A recorded sentence embedded in speech spectrum noise at +5 dB signal to noise ratio was presented to a four channel digital hearing aid and the output was recorded with different combinations of algorithms at 30, 45 and 70 dB HL levels of presentation through a 2 cc coupler. EDI and LLR were obtained in comparison with the original signal using MATLAB software. In addition, thirty participants with normal hearing sensitivity rated the output on the loudness and clarity parameters of quality. The results revealed that the temporal changes happening at the output is independent of the number of algorithms activated together in a hearing aid. However, at a higher level of presentation, temporal cues are better preserved if all of these algorithms are deactivated. The spectral components speech tend to get affected by the presentation level. The results also indicate the importance of quality rating as this helps in considering whether the spectral and/or temporal deviations created in the hearing aid are desirable or not. Full article

There is a considerable debate on the use of hearing aid in children with auditory dys-synchrony (AD). To current date there are no similar Studies which show the effect of acoustic amplification on outcomes on speech and language development in children with AD are found in the literature. Thus, in the present study three children diagnosed to have AD were recruited and subjected to hearing aid trial and fitting based on the late latency response thresholds. Ranging from 7 months to 41 months of intervention period, each child’s language age was reassessed and compared with that of their pre-therapy language age. The comparison showed a good improvement in receptive age, though the children had moderate to severe degree of hearing loss. But their expressive age was significantly delayed irrespective of their age of identification and duration of intervention. Thus the delay in expression with a good amount of improvement in reception can be a characteristic of an AD child with amplification. Full article

The study aimed at understanding the psychoacoustic characteristics of tinnitus in individuals with auditory neuropathy spectrum disorder (ANSD). It attempts to assess the pitch and intensity of loudness of tinnitus matched by individuals with ANSD. Fifty individuals who were diagnosed as having auditory neuropathy spectrum disorder were included in the study. Tinnitus evaluation was carried out where the individuals matched the frequency and intensity of loudness of the tinnitus. The results of the study shows that pitch matched by majority of patients with ANSD is predominantly low pitched (<1000 Hz). The frequency of tinnitus matched by the patients with ANSD also correlated with the degree of maximal hearing loss. The intensity of loudness of the tinnitus was around 10-15 dB higher than their threshold in majority of the patients considered in the study. There was a weak negative correlation for the matched frequency and intensity of loudness. The results of the study suggest that majority of individuals with low frequency hearing loss had low pitched tinnitus. Thus, there could be discordant damage between outer and inner hair cells, abnormal firing of auditory nerve in individuals with ANSD which can lead to tinnitus. Thus, it can help to understand the physiology of tinnitus in individuals with ANSD. Full article

Past work has shown relationship between the ability to discriminate spectral patterns and measures of speech intelligibility. The purpose of this study was to investigate the ability of both children and young adults to discriminate static and dynamic spectral patterns, comparing performance between the two groups and evaluating within- group results in terms of relationship to speech-in-noise perception. Data were collected from normal-hearing children (age range: 5.4-12.8 years) and young adults (mean age: 22.8 years) on two spectral discrimination tasks and speech-in-noise perception. The first discrimination task, involving static spectral profiles, measured the ability to detect a change in the phase of a low-density sinusoidal spectral ripple of wideband noise. Using dynamic spectral patterns, the second task determined the signal-to-noise ratio needed to discriminate the temporal pattern of frequency fluctuation imposed by stochastic lowrate frequency modulation (FM). Children performed significantly poorer than young adults on both discrimination tasks. For children, a significant correlation between speech-in-noise perception and spectral- pattern discrimination was obtained only with the dynamic patterns of the FM condition, with partial correlation suggesting that factors related to the children’s age mediated the relationship. Full article

Speech evoked auditory brainstem responses depicts the neural encoding of speech at the level of brainstem. This study was designed to evaluate the neural encoding of speech at the brainstem in younger population and middle-aged population at three different repetition rates (6.9, 10.9 and 15.4). Speech evoked auditory brainstem response was recorded from 84 participants (young participants=42, middle aged participants=42) with normal hearing sensitivity. The latency of wave V and amplitude of the fundamental frequency, first formant frequency and second formant frequency was calculated. Results showed that the latency of wave V was prolonged for middle-aged individuals for all three-repetition rates compared to the younger participants. The results of the present study also revealed that there was no difference in encoding of fundamental frequency between middle aged and younger individuals at any of the repetition rates. However, increase in repetition rate did affect the encoding of the fundamental frequency in middle-aged individuals. The above results suggest a differential effect of repetition rate on wave V latency and encoding of fundamental frequency. Further, it was noticed that repetition rate did not affect the amplitude of first formant frequency or second formant frequency in middle aged participants compared to the younger participants. Full article

Amidst several publications reporting the effects of stimulus-related parameters on ocular vestibular evoked myogenic potential (oVEMP), the effect of the repetition rate on oVEMP responses has largely gone unexplored. Studies have used a repetition rate of ~5.1 Hz mainly due to a presumption that oVEMP, like cervical VEMP, should produce best responses for ~5 Hz, although there is paucity of experimental evidence to support this hypothesis. 52 healthy individuals in the age range of 17-35 years underwent air-conduction oVEMP elicited by 500 Hz tone-bursts using seven different repetition rates (3.1, 5.1, 10.1, 15.1, 20.1, 25.1 and 30.1 Hz). The results revealed a tendency for prolongation of latencies and reduction in amplitude with increasing repetition rate. However, significantly longer latencies were observed only for 20.1 Hz and larger amplitudes for 3.1 and 5.1 Hz (P<0.05). There was no significant difference between the rates of 3.1 Hz and 5.1 Hz. However 3.1 Hz produced poorer signal-to-noise ratio and required considerably longer time and thereby had lesser efficiency than 5.1 Hz (P<0.05). This would also result in higher fatigue and irritation levels considering the physical act of maintaining a supero-medial gaze. Thus the use of 5.1 Hz is recommended for clinical recording of oVEMP. Full article

The following objectives of the study were formulated: i) to investigate differences in measured signal to noise ratios while recording speech-evoked auditory brainstem response (cABR) and cortical late latency response (LLR) in low and high acceptable noise level (ANL) groups; and ii) to compare peak to peak amplitude of cABR (V-A) and LLR (N1-P2) in low and high ANL groups. A total of 23 normal hearing participants was included in the study. One shot replicative and partly exploratory research design was utilized to study the effect of signal to noise ratio in a recorded waveform on afferent mechanism, assessed by cABR and LLR on participants having values of ANL of ≤7 (low ANL group) and ≥13 (high ANL group). There were no differences in signal to noise ratio in the recorded waveforms of cABR and LLR between low and high ANL groups at both brainstem and cortical levels. However, the peak to peak amplitude of V-A of cABR and N1-P2 of LLR were both statistically larger in the high ANL group compared to their counterpart. The signal to noise ratio in recorded waveforms did not differentiated cABR (V-A) or LLR (N1-P2) in low and high ANL groups. However, Larger peak to peak amplitudes in the high ANL group suggests differences higher processing centers in the upper brainstem to the auditory cortex. The findings of the study may be useful in determining the patient acceptability of noise. Full article

The aim of the study was to assess speech recognition in noise using multitalker babble of native and non-native language at two different signal to noise ratios. The speech recognition in noise was assessed on 60 participants (18 to 30 years) with normal hearing sensitivity, having Malayalam and Kannada as their native language. For this purpose, 6 and 10 multitalker babble were generated in Kannada and Malayalam language. Speech recognition was assessed for native listeners of both the languages in the presence of native and nonnative multitalker babble. Results showed that the speech recognition in noise was significantly higher for 0 dB signal to noise ratio (SNR) compared to -3 dB SNR for both the languages. Performance of Kannada Listeners was significantly higher in the presence of native (Kannada) babble compared to non-native babble (Malayalam). However, this was not same with the Malayalam listeners wherein they performed equally well with native (Malayalam) as well as non-native babble (Kannada). The results of the present study highlight the importance of using native multitalker babble for Kannada listeners in lieu of non-native babble and, considering the importance of each SNR for estimating speech recognition in noise scores. Further research is needed to assess speech recognition in Malayalam listeners in the presence of other non-native backgrounds of various types. Full article

The temporal difference limen (TDL) can be measured with noninvasive electrical ear canal stimulation. The objective of the study wa to determine the role of preoperative TDL measurements in predicting patients’ speech perception after cochlear implantation. We carried out a retrospective chart analysis of fifty-four cochlear implant (CI) patients with preoperative TDL and postoperative bisyllabic word recognition measurements in Helsinki University Central Hospital between March 1994 and March 2011. Our results show that there is no correlation between TDL and postoperative speech perception. However, patient’s advancing age correlates with longer TDL but notdirectly with poorer speech perception. The results are in line with previous results concerning the lack of predictive value of preoperativ TDL measurements in CI patients. Full article