At high fundamental frequencies (fos), wide harmonic spacing can obscure typical formant cues. This study investigates the role of static spectral cues in maintaining vowel identity under such conditions. We resynthesized steady-state versions of eight German vowels (/i, y, e, ø, ɛ, a, o, u/) across fos ranging from 220 to 880 Hz from previously identifiable spoken vowels, preserving their gross spectral shapes. Twenty native German speakers participated in a two-alternative forced-choice identification task. Results showed that identification accuracy declined at higher fos, especially for vowels with less distinctive spectral features, sometimes approaching chance levels. However, vowels with more distinctive static spectral properties, particularly the point vowels /i/, /a/, and /u/, often remained identifiable above chance even at the highest fos. Auditory excitation patterns indicated that listeners rely on perceptual anchors at the boundaries of the vowel space, utilizing gross static spectral properties to maintain vowel contrasts when harmonic spacing undersamples the vocal tract transfer function. These findings suggest that the auditory system adapts to challenging acoustic conditions by relying on internal representations of vowel categories and static spectral cues, highlighting their importance in preserving vowel identity at high fos.