A good microphone needs flat response from 20 Hz to 20 kHz.

Evidence

The function of a microphone is to transform a sound signal (typically pressure) propagating in the air into a corresponding electrical signal (voltage) (Eargle, 2004). A good microphone should convert a wide range of frequencies, say from 20 Hz to 20 kHz, with a flat frequency response, low distortion and noise, and have a desired directional pattern. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 481

Categorization

• DEFINE: Establishes the formal specification of microphone performance (flat frequency response, low distortion/noise, directional pattern).
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 481