B&K 3361

Speech Transmission Index Meter - RASTI

£ 24 a day *

Rapid Speech Transmission Index Meter 3361 measures RASTI values directly using two instruments

Speech Transmitter type 4225 which sends out a special test signal and Speech Receiver type 4419 which analyses the signal and calculates the RASTI value.

The instruments are battery powered and fully portable, enabling rapid and objective measurement of the quality of speech intelligibility and provide further information of diagnostic value

Uses : ♦  Objective assessment of speech intelligibility in: Auditoria, Theatres, Conference rooms, Schools, Industry, Aircraft etc., ♦  Optimising speech reinforcement systems ♦  Assessment of public address systems: in Railway Stations, Airports, also Emergency Public Address Systems ♦  As a diagnostic tool for investigating means of improving speech intelligibility ♦  Investigation of acoustical privacy Features : ♦  Measures Speech Transmission Index according to RASTI method ♦  Speech transmission index given for two octave bands of carrier signal ♦  Measures 9 points on Modulation Transfer Function ♦  Estimates equivalent Early Decay and equivalent S/N ♦  RASTI index can be compared with results of theoretical models ♦  Built-in loudspeaker for output of test signal ♦  Selectable measuring times of 8, 16 and 32 s ♦  Provision for entry of noise floor to simulate background noise ♦  Easily calibrated ♦  Instruments are small and battery operated

The system is in two parts:-

Speech Transmitter type 4225
Sends out a special test signal, either directly or over the PA system

Speech Receiver type 4419
Analysis the signal and calculate the RASTI and other values.

The technique is documented in BS EN 60268

Manufacturer's Specifications

The B&K 3361 RASTI kit includes a B&K microphone with a 1.5 m lead to the 4419 speech receiver. A tripod for the 4225 speech transmitter and a XLR output plug for connecting to your PA system.

If the hall or space you are testing does not have a sound system and you require a suitable amplifier / speaker then order a Norsonic 250 /260 system.

Add a calibrator and


* Our standard hire charges are based on a 4-day minimum period - details and other options.

Gracey & Associates   01933 624212

BSI accreditation for instrument hire and calibration

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