Concerning to the equipments, the DTM has at its disposal, a 24 multichannel real time spectrum analyzer with its corresponding transducers (microphones and accelerometers), an impact hammer, a tapping machine, a vibration exciter and a dodecahedral speaker, among others. Regarding to facilities, the DTM has a full anechoic chamber, a reverberation chamber, a full equipped recording studio and a tank for underwater acoustics. A more detailed description of these facilities is next provided.
Full anechoic chamber:
The anechoic chamber is used to conduct acoustic measurements in free field conditions. All sound energy emanating from a source inside the chamber propagates with non-reflecting back. This is achieved by recovering the room with pyramidal acoustically absorbent material. Vibration isolators separate it from the rest of the building to avoid any structure-borne noise path that could alter its anechoic properties.
Anechoic chamber main features:
General data:
Volume without absorbent material: 517 m3
Volume with absorbent material: 215 m3
Total suspended mass: 120•103 Kg
Dimensions:
Width: 6.13 m
Height: 4.4 m
Length: 8.9 m
Acoustics characteristics:
Ressonant frequency: 11 Hz
Cutoff frequency: 70 Hz
Transmission Loss at 1KHz: 80 dB
Residual noise: 15 dB(A)
Reverberation chamber
The reverberation chamber is used to perform acoustic experiments in diffuse field conditions. It has been designed to have a high reverberation time (TR60) for all frequency bands. All inner sides are recovered with acoustically reflecting materials and it has non-parallel walls and an irregular roof. Consequently, only a very small percentage of energy is lost at each reflection, and the chamber presents a good distribution of eigenmodes.
Reverberation chamber main features:
General data:
Volume: 231 m3
Total surface: 211 m2
Floor surface: 44.6 m2
Acoustics characteristics:
Residual noise: 40 dB SPL, 16 dB(A)
Transmission Loss at 1KHz: 50 dB
Reverberation time:
Freqency (Hz) / TR60 (s)
125 11.5
250 11
500 10.5
1000 10
2000 7.25
4000 5
8000 2.25
Recording Studio
The recording studio consists in two separate spaces: a control room and a recording room. The control room hosts the hardware that the sound engineer uses to perform sound recording and mixing tasks. The studio is based on a digital sound platform and allows simple intercom between control and recording room. The room is acoustically treated with perforated wooden panels and with absorbent materials on the inner side. The objective of these panels is to make the room’s frequency response as neutral as possible to ensure maximum transparency for the monitoring of recorded audio signals.
Control room equipment:
Microphones:
1x AKG D112
4x Shure SM57
4x Shure SM58
2x AKG 414 ULS
2x AKG C1000B
2x AKG C391B
2x Audiotechnica 4033
2x Shure Beta 91
Recording system:
Focusrite Octopre Preamp
Digidesign Protools HD96I/O + Apple MAC G5
Digidesign Control 24 Mixing Desk and Controller
Editing & mixing:
Protools 7.4 + Pro-tools HD|3 plugins
Digidesign Control 24 Mixing Desk and Controller
Monitoring:
Dynaudio AIR15 Stereo Pair
Behringer Powerplay HA4700 Headphone Amplifier
AKG Headphones
Backline and additional gear:
Roland A30 MIDI Keyboard
Roland XV-3080 GM Module
TC Electronic M-One Multi FX Processor
Alesis 3630 Compressor / Gate
ESI Miditerminal M8U MIDI Switch
Yamaha Stage Custom Drumset
Hartke 5500 Bass Amp + VX115 Cabinet
Ibanez MIMX150H Guitar Amp
Native Instruments KOMPLETE
The recording room is where musicians, speakers and other artists are recorded. To reduce the impact of room modes on the recording, the room’s ceiling has been made non-parallel to the floor. The absorbent curtains, together with the installed resonators allow having different acoustic environments that can be easily configured. There also is an acoustic door that connects the recording room to the reverberant chamber, which can be use to record special reverberation effects.
Tank for underwater acoustics
The DTM also has a small water tank (about 8m³) to carry out underwater acoustics measurements. Hydrophones can be positioned using specially designed guides and an annex room is used to record all measurements. The tank can be used for example to make studies on water sound speed or reflection phenomena.
