Fine structure processing improves telephone speech perception in cochlear implant users
Department of Otolaryngology-Head and Neck Surgery, University Hospital La Paz, Secretaria de Otorrinolaringología, 4th Floor, Paseo de la Castellana 261, 28046, Madrid, Spain, . Archives of Oto-Rhino-Laryngology
(Impact Factor: 1.55).
07/2012; 270(4). DOI: 10.1007/s00405-012-2101-9
The objective of this study was to compare telephone speech perception and subjective preferences in cochlear implant users with two different speech-processing strategies: high-definition continuous interleaved sampling (HDCIS) and fine structure processing (FSP). A randomized double-blind study was designed for intra-individual comparison of HDCIS and FSP. Twenty-five post-lingually deafened patients with either the PulsarCI(100) or SonataTI(100) and Opus2 acoustic processor were tested consecutively with both coding strategies, assigned in a random order. Disyllabic word speech perception was tested 6 weeks after each fitting under the following conditions: landline use with (LWN) and without (LWoN) background noise, mobile use with (MWN), and without (MWoN) background noise and mobile use with a Bluetooth magnetic field transmitter necklace (MB). Changes in health-related quality of life (QoL) were assessed using the Glasgow Benefit Inventory (GBI) and Faber's questionnaire. Personal preferences between strategies were surveyed upon completion of the study. All subjects included in this study performed better with FSP in the landline tests. There was an improvement of 11.5 % in LWN use (p = 0.014; CI 95 % = 3-20 %) and 10 % in LWoN use (p = 0.001; CI 95 % = 5-15 %). MWoN showed an improvement of 6.3 % with FSP (p = 0.03; CI 95 % = 0-13 %). MB tests showed an improvement of 11 % with FSP (p < 0.05; CI 95 % = 1.5-22 %). Quality of life was significantly better using FSP. Eighty-four percent of participants preferred FSP. The FSP speech coding strategy improved the speech recognition of cochlear implant users when using the telephone compared to HDCIS. Cochlear implantation with FSP coding improved QoL.
Available from: Han-Gyol Yi
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ABSTRACT: Impaired perception of consonants by poor readers is reflected in poor subcortical encoding of speech timing and harmonics. We assessed auditory brainstem representation of higher harmonics within a consonant-vowel formant transition to identify relationships between speech fine structure and reading. Responses were analyzed in three ways: a single stimulus polarity, adding responses to inverted polarities (emphasizing low harmonics), and subtracting responses to inverted polarities (emphasizing high harmonics). Poor readers had a reduced representation of higher speech harmonics for subtracted polarities and a single polarity. No group differences were found for the fundamental frequency. These findings strengthen the evidence of subcortical encoding deficits in poor readers for speech fine structure and delineate effective strategies for capturing these neural impairments in humans.
Available from: Samira Anderson
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ABSTRACT: Individuals with sensorineural hearing loss often report frustration with speech being loud but not clear, especially in background noise. Despite advanced digital technology, hearing aid users may resort to removing their hearing aids in noisy environments due to the perception of excessive loudness. In an animal model, sensorineural hearing loss results in greater auditory nerve coding of the stimulus envelope, leading to a relative deficit of stimulus fine structure. Based on the hypothesis that brainstem encoding of the temporal envelope is greater in humans with sensorineural hearing loss, speech-evoked brainstem responses were recorded in normal hearing and hearing impaired age-matched groups of older adults. In the hearing impaired group, there was a disruption in the balance of envelope-to-fine structure representation compared to that of the normal hearing group. This imbalance may underlie the difficulty experienced by individuals with sensorineural hearing loss when trying to understand speech in background noise. This finding advances the understanding of the effects of sensorineural hearing loss on central auditory processing of speech in humans. Moreover, this finding has clinical potential for developing new amplification or implantation technologies, and in developing new training regimens to address this relative deficit of fine structure representation.
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The aim of the present study was to compare two novel fine structure strategies "FS4" and "FS4-p" with the established fine structure processing (FSP) strategy. FS4 provides fine structure information on the apical four-electrode channels. With FS4-p, these electrodes may be stimulated in a parallel manner. The authors evaluated speech perception, sound quality, and subjective preference.
A longitudinal crossover study was done on postlingually deafened adults (N = 33) who were using FSP as their default strategy. Each participant was fitted with FS4, FS4-p, and FSP, for 4 months in a randomized and blinded order. After each run, an Adaptive Sentence test in noise (Oldenburger Sentence Test [OLSA]) and a Monosyllable test in quiet (Freiburger Monosyllables) were performed, and subjective sound quality was determined with a Visual Analogue Scale. At the end of the study the preferred strategy was noted.
Scores of the OLSA did not reveal any significant differences among the three strategies, but the Freiburger test showed a statistically significant effect (p = 0.03) with slightly worse scores for FS4 (49.7%) compared with FSP (54.3%). Performance of FS4-p (51.8%) was comparable with the other strategies. Both audiometric tests depicted a high variability among subjects. The number of best-performing strategies for each participant individually was as follows: (a) for the OLSA: FSP, N = 10.5; FS4, N = 10.5; and FS4-p, N = 12; and (b) for the Freiburger test: FSP, N = 14; FS4, N = 9; and FS4-p, N = 10. A moderate agreement was found in the best-performing strategies of the Speech tests within the participants. For sound quality, speech in quiet, classical, and pop music were assessed. No significant effects of strategy were found for speech in quiet and classical music, but auditory impression of pop music was rated as more natural in FSP compared with FS4 (p = 0.04). It is interesting that at the end of the study, a majority of the participants favored the new coding strategies over their previous default FSP (FSP, N = 13; FS4, N = 13; FS4-p, N = 7).
In summary, FS4 and FS4-p offer new and further options in audio processor fitting, with similar levels of speech understanding in noise as FSP. This is an interesting result, given that the strategies' presentation of temporal fine structure differs from FSP. At the end of the study, 20 of 33 subjects chose either FS4 or FS4-p over their previous default strategy FSP.
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