The Band-Importance Function for the Korean Standard Sentence Lists for Adults.

BACKGROUND AND OBJECTIVES: The band-importance function (BIF) refers to a value characterizing the relative importance of different frequencies to speech intelligibility. The purpose of this study was to derive the BIF for the Korean standard sentence lists for adults (KS-SL-A). SUBJECTS AND METHODS: In this study, sentences from the KS-SL-A were used as the speech material. Twenty-six normal-hearing Korean listeners participated and intelligibility scores in 8 filters with 3 signal-to-noise ratio conditions were obtained. Based on the intelligibility score percentages, the BIF for the KS-SL-A was derived by using an established protocol. RESULTS: Band-importance weights varied across frequency bands. The most important frequency region was around 316 Hz (20.0%), and the importance of the frequency bands below the center frequency (CF) of 1,778 Hz was 59.6%. Therefore, low frequencies below the CF of 1,778 Hz were more important than high frequencies above the CF of 1,778 Hz. CONCLUSIONS: The BIF for KS-SL-A could be applied towards developing a hearing aid fitting formulae for Korean listeners.

Phoneme-based self hearing assessment on a smartphone.

Phonemes provide an interesting alternative to pure tones in hearing tests.We propose a new smartphone-based method for self-hearing assessment using the four Korean phonemes which are similar to the English phonemes /a/, /i/, /sh/, and /s/. We conducted tests on 15 subjects diagnosed with mild to severe hearing loss and estimated their conventional pure-tone hearing thresholds from their phoneme hearing thresholds using regression analysis. The phoneme-based self-hearing assessment was found to be sufficiently reliable in estimating the hearing thresholds of hearing impaired subjects. The difference between the hearing thresholds obtained through conventional pure-tone audiometry and those obtained using our method was 5.6 dB HL on average. The proposed hearing assessment was able to significantly reduce the mean test time compared to conventional pure-tone audiometry.

Noise reduction for binaural hearing aids using unsupervised diffuse noise estimator.

In this paper a new noise reduction algorithm for binaural hearing aids is proposed. This algorithm is capable of suppressing both nonstationary diffuse noise and unknown directional interferences without distorting the directional cues. For the estimation of the diffuse noise power spectral density (PSD), we utilize the eigenstructure of the 2 × 2 input covariance matrix, together with a compensation process for preventing the underestimation at low frequencies. The interference PSD is estimated from the target cancelled input signals through the signal prediction. Effectiveness of the proposed algorithm was confirmed according to the computer simulations in terms of noise reduction and binaural cue preservation.

Study on self hearing assessment using speech sounds.

In this study, we proposed new self assessment of hearing loss in mobile phones and realized a function of compensation for hearing impaired person. The results of experiments on mobile phone showed that the proposed hearing test is sufficient to check hearing loss and the compensation based on the result of the proposed hearing test can improve speech intelligibility of hearing impaired persons.

Robust adaptive feedback canceller based on modified pseudo affine projection algorithm.

This paper presents an adaptive feedback cancellation (AFC) algorithm with robust and stable performance. The proposed algorithm is based on the pseudo affine projection (PAP) algorithm which approximates the affine projection (AP) with a complexity comparable to the NLMS. Direct application of the PAP to AFC, however, often exhibits instability because of the delayed estimate of the linear prediction (LP) coefficients. This problem is solved in the proposed algorithm by utilizing an inverse gain filter (IGF) before the update of adaptive filter and by estimating the LP coefficients from the input signal without delay. Simulation results confirmed robustness and stability of the proposed algorithm.