© Emily Shannon Fu Foundation
Telephone speech training module is designed to improve the recognition performance of bandlimited speech (telephone speech) for hearing impaired listeners. This module is similar to the basic module except that the frequency range of all acoustic sounds is limited to telephone bandwidth (300-3200 Hz). Here shows the example of original and telephone bandlimited waveform and spectrum.  The training groups in this module include: Group 1: Pure Tones – practice identifying different pitches Pure tones within the frequency range of 300-3200 Hz are not affected. Any pure tones out of this range will be severely attenuated. Some listeners may not be able to hear any sounds outside of this range. Some performance degradation is expected with this training group. Since some sounds are highly attentuated, the training is designed to help the listener recognize very soft sounds. Group 2: Environmental Sounds – practice identifying common environmental sounds There will be little change in one’s ability to recognize environmental sounds that have limited high frequency components. However, recognition performance of those environmental sounds that include high frequency components will be significantly reduced. It is expected that overall recognition performance will be reduced with bandlimited. The training will help the listener focus on the available spectral cues and discriminate different sounds with limited spectral information. Group 3: Male/Female Identification - practice discriminating between speakers Recent studies have shown that the voice gender recognition can be significantly affected by bandliming (Horng et al., Ear and Hearing, 28(2), Suppl. 66S-69S). Loss of high frequency information weakens the spectral contrast and results in lower recognition performance. The training will aid the listener to focus on the periodicity cue to discriminate voice gender and improve overall voice gender recognition performance. Group 4: Vowel Recognition - practice vowel discrimination and identification Vowel recognition is highly dependent on the F1 and F2 formant frequencies. Since these are within telephone bandwidth, vowel recognition performance is not significantly affected by bandlimiting for English. However, vowel recognition performance is significantly reduced with telephone speech for other languages such as Chinese. One reason is that some Chinese vowels are dependent on the spectral difference in the high frequency region (e.g., YI versus YU). The loss of high frequency information makes it difficult to discriminate these vowels in the Chinese language. Group 5: Consonant Recognition - practice consonant discrimination and identification Consonant recognition is highly dependent on high frequency components. The loss of high frequency components in bandlimiting speech may significantly reduce the recognition performance of consonants. The training will help the listener to utilize other available cues to discriminate different consonants. Group 6: Word Discrimination – practice common words from four different topic categories Word recognition will be affected by the loss of high frequency components with telephone speech since words generally include both vowel and consonant segments. Since English vowel recognition is not affected by telephone bandwidth, performance will be more dependent on consonants. Some words will be more affected by bandlimiting than others. The training will aid the listener to utilize the available spectral cues to discriminate different words. Group 7: Everyday Sentences – practice identifying sentences with different levels of background noise Sentence recognition is one of the listening tasks which will be most affected by bandlimits. Recent studies show a near 20% drop in recognition performance with limited bandwidth [Fu, Q.-J. and Galvin, J.J. III (2006). “Recognition of Simulated Telephone Speech by Cochlear Implant Patients,” Am J Audiol. 15(2), 127-132]. The training will aid the listener to utilize available spectral cues to understand sentences. Group 8: Music Appreciation – practice identifying musical instruments and familiar tunes to aid music appreciation Some musical instruments and familiar tunes may not be affected by bandlimiting if their frequency ranges are primarily within the 300-3200 Hz.  Otherwise, recognition performance will be impacted by the bandlimits.
Angel SoundTM Basic Phone Noise Melodic Music Openset Auditory Assess Scene Telephone Speech Angel SoundTM: Telephone Speech Training Normal Speech Phone