The Brüel & Kjær 4227 Mouth Simulator is an acoustic test instrument that replicates the sound field characteristics of the human mouth for precise calibration and measurement of audio equipment. It generates standardized acoustic output across telecommunications, hearing aid manufacturing, and acoustic research applications while meeting IEEE 269, IEEE 661, and ITU-T P.51 standards.
## Technical Specifications
**Acoustic Output**
• Continuous SPL: minimum 110 dB SPL (200 Hz to 2 kHz) and minimum 100 dB SPL (100 Hz to 8 kHz) at 25 mm from lip ring
• Pulsed operation: exceeds 120 dB SPL at 25 mm distance (up to 50 W for periods <2 seconds with 20-second intervals)
• Mouth opening diameter: 20 mm at lip ring
• Low distortion characteristics
**Frequency Response**
• Achieves ±1 dB deviation or better across 100 Hz to 10 kHz at 25 mm distance with equalization via ¼″ monitoring microphone in compressor loop
**Power**
• Maximum continuous consumption: 10 W
• Short-duration operation: up to 50 W
• Type 4227-A includes built-in Class D amplifier
## Key Features
• Built-in overload protection circuit for loudspeaker safety
• Monitoring microphone provision: accepts Brüel & Kjær ¼″ microphone with ¼″ preamplifier for output level monitoring and frequency response optimization
• Removable plastic dummy ¼″ microphone maintains consistent acoustic characteristics with or without active monitoring microphone installed
• Supplied with UA-0901 calibration jig positioning ½″ measuring microphone at 25 mm from lip ring
## Standards Compliance
Conforms to IEEE 269, IEEE 661, and ITU-T Recommendation P.51 for human mouth sound field replication.
## Typical Applications
• Telecommunications equipment testing
• Hearing aid calibration and verification
• Acoustic measurement and research
