For example: Agilent E4440A or Anritsu 68369
Audio Test Instruments
Audio Precision P1
Portable One, 10Hz-120kHz Audio Distortion Analyzer

Manufacturer: Audio Precision
Audio Precision P1PLUS
Portable One Plus,10Hz-120kHz Audio Distrtn Anlyzer

Manufacturer: Audio Precision
Audio Precision SYS-202
Dual Channel, DSP Analyzer Only Audio Test System

Manufacturer: Audio Precision
Audio Precision SYS-2722A
System 2 Cascade Plus PC-Controlled Audio Test System

Manufacturer: Audio Precision
Audio Precision SYS-302
Dual Channel, Dual Domain Audio Analyzer System

Manufacturer: Audio Precision
Rohde and Schwarz UP300
Audio Analyzer 10 Hz to 80 kHz Analog Interfaces

Manufacturer: Rohde and Schwarz
Rohde and Schwarz UPA-3
10 Hz to 100 kHz Audio Analyzer (With Generator)

Manufacturer: Rohde and Schwarz