title: Nonlinear frequency compression: Influence of start frequency and input bandwidth on consonant and vowel recognition.
abstract: By varying parameters that control nonlinear frequency compression (NFC), this study examined how different ways of compressing inaudible mid- and/or high-frequency information at lower frequencies influences perception of consonants and vowels. Twenty-eight listeners with mild to moderately severe hearing loss identified consonants and vowels from nonsense syllables in noise following amplification via a hearing aid simulator. Low-pass filtering and the selection of NFC parameters fixed the output bandwidth at a frequency representing a moderately severe (3.3 kHz, group MS) or a mild-to-moderate (5.0 kHz, group MM) high-frequency loss. For each group (n = 14), effects of six combinations of NFC start frequency (SF) and input bandwidth [by varying the compression ratio (CR)] were examined. For both groups, the 1.6 kHz SF significantly reduced vowel and consonant recognition, especially as CR increased; whereas, recognition was generally unaffected if SF increased at the expense of a higher CR. Vowel recognition detriments for group MS were moderately correlated with the size of the second formant frequency shift following NFC. For both groups, significant improvement (33%-50%) with NFC was confined to final /s/ and /z/ and to some VCV tokens, perhaps because of listeners' limited exposure to each setting. No set of parameters simultaneously maximized recognition across all tokens.
authors.affiliation: Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Alexander
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001302:Audiometry, Speech; D001309:Auditory Threshold; D003463:Cues; D005260:Female; D034381:Hearing Loss / Q000175:diagnosis / Q000523:psychology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects; D017711:Nonlinear Dynamics; D010470:Perceptual Masking; D010898:Pitch Perception; D021641:Recognition, Psychology; D012720:Severity of Illness Index; D013018:Sound Spectrography; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D014833:Voice Quality