In front‐back vowel continua cued by variations ofF2, a critical‐band (Z) representation of formant frequency was found to relate linearly to the judged “phonetic goodness” of the vowels: changes inF2 (ΔF2) which are equal along theZscale, produce nearly equal changes of judged “phonetic‐goodness” (ΔG) [Espinoza‐Varas, J. Acoust. Soc. Am. Suppl. 174,S66 (1983)]. We replicated the previous experiments in sensorineural impaired listeners (low‐frequency hearing loss, gradually sloping audiograms), who typically exhibit broadened critical bands. The vowel continua ranged from /u/ to /i/, /ɔ/ to /ɛ/, or /a/ to /æ/. On each continua the frequencies ofF1 andF3 were fixed, and the frequency ofF2 varied from the value appropriate for the back vowel to that appropriate for the front vowel in 6–12 steps of 0.5Zeach.F0 was 120 Hz. The 400‐ms, steady‐state vowels were generated by parallel synthesis; listeners categorized the stimuli and rated their “phonetic goodness.” A highly consistent deficit (across subjects and vowel pairs) in the impaired listeners' performance is the poorer ability to assess how good an examplar of a vowel class a given stimulus is. The relation between ΔF2 and ΔGis no longer linear. This deficit is observed even though the ability to identify the vowels may be “normal.” The results appear to corroborate the possibility of a close relation between the judgment of “phonetic goodness” of vowels and the critical‐band level of frequency analysis [Supported by AHFMR and NSERC.]