This is a room where sound reflections only come from the floor because the walls and ceiling are absorbent. The solid floor makes this room much easier to work in than the anechoic chamber, because equipment can be stood on the solid floor. Often, we put absorbent material on the floor to reduce floor reflections.
Example application – diffuser scattering
The standard method for testing room acoustic diffusion coefficients was developed as part of a research project at Salford. The most efficient method is done in a semi-anechoic chamber with all the microphones, the loudspeaker and diffuser sample placed on the hard floor in a boundary plane measurement. The absorbent walls and ceiling then prevent unwanted reflections. The room is quiet so background noise doesn’t affect measurement accuracy.
Example application – public engagement
Television has always enjoyed filming in our anechoic chambers. Our first chamber was used as a mock up of a torture chamber for Granada TV, and more recently, Richard Hammond was filmed by National Geographic breaking a glass using the sound from his guitar. Producers like the anechoic chamber, but often use the semi-anechoic because of problems setting up equipment on a trampoline floor. We filmed high speed footage of acoustic phenomena in this room, and have used it to make videos for use in classrooms. See www.acoustics.salford.ac.uk/schools
- Background noise level 3.8dBA
- Working volume 4.2m x 3.3m x 3.0m
- Cut-off frequency 250Hz
Tests & Standards
Sound power level measurement to BS ISO 3744 / ISO 3745 and BS 4196
Student semi-anechoic room
The student anechoic room is part of the student audio and acoustics laboratory. It is used exclusively for teaching. Typically it is used for noise measurement in the Applications of Acoustics module and for measuring the response of loudspeakers in the Electroacoustic Transducer Design module.
Studios and laboratories
- Audio production suites - containing PCs and Macs for audio production using Pro Tools and Reason.
- Video post production suites - containing PCs and Macs for video production using Final Cut Pro and Adobe Creative Suite.
- TV Studios - containing PCs and Macs for video production using Final Cut Pro and Adobe Creative Suite.
- Radio Studios - containing PCs and Macs for video production using Final Cut Pro and Adobe Creative Suite.
- Digital Media Performance Lab - a 100 seat multi-media performance space used for live sound.
- Recording studios - a set of four fully acoustically treated studios, each with its own live room.
- Anechoic chamber - a room with no echoes used to measure, for example, directionality of loudspeakers. Includes a virtual tour.
- Semi-anechoic chambers
- Reverberation chambers - rooms with little absorption, used to measure, for example, the absorption of concert hall seating. Includes a virtual tour.
- Transmission suite - two rooms used to measure how much sound goes through the walls of buildings
- Listening room - used to carry out subjective tests, for example on audio quality.
- Undergraduate laboratory - for electronics and acoustics, audio and video experiments.
- Project laboratory - containing specialist experimental equipment for final year, MSc and research projects.
- Computer laboratories - a set of PC labs for teaching programming, web design and digital audio processing.