Acoustic Calculator

Fifty-two acoustics and audio calculators that show you how they got there. You are standing in the room and somebody asks how much absorption it needs. You can give them a figure in about ten seconds. Then a fortnight later, when the builder asks where that figure came from, you can show them the formula, your own numbers in it, and what it assumed. That is the whole idea. Every calculator here opens onto its own working. WHAT IT COVERS Room acoustics. Reverberation time, how much absorption a room needs and which material will actually do it, room modes, critical distance, NR and NC ratings, speech intelligibility. Systems and rigging. Loudspeaker SPL, amplifier headroom, 70 V and 100 V lines, cable loss, crossovers, compressor settings, gain before feedback, pan law. Propagation. Speed of sound, atmospheric absorption over a long throw, delay times for a fill, comb filtering, Doppler shift. Levels, hearing, music and files. SPL and pressure and power, noise exposure dose, A, C and Z weighting, equal loudness contours, critical bands, tempo and pitch, file sizes, buffer latency, timecode. WORK BACKWARDS FROM THE ANSWER Sometimes the result is the thing you already know. The room has to reach 0.6 seconds. The rig has to make 102 dB. Type the figure you need into the answer and the calculator tells you what would get you there, and what each route would cost you. IT TELLS YOU WHEN IT IS UNSURE Acoustics is full of approximations that hold until they do not. Sabine's equation is flagged once a room is too absorptive for it. The speech figure says plainly that it is an estimate rather than a measurement. The crossover calculator refuses to print fourth-order component values, because they depend on a driver impedance it cannot know. You will not be handed a confident number that had no business being confident. BUILT FOR WHERE THE WORK HAPPENS Plant rooms, basements, the back of a hall. The places you need this are the places with no signal, so everything runs on the device. Nothing is collected, nothing is uploaded, and there is no account to make. Octave band spectra are bars you drag like a graphic equaliser, so you can see the shape of a spectrum while you are entering it. WHERE THE NUMBERS COME FROM ISO 9613-1 atmospheric absorption. ISO 226:2003 equal loudness. IEC 61672-1 weighting. ISO and ANSI noise rating curves. IEC 61260-1 bands. The arithmetic is shared with an open-source analysis library that is tested against the standards' own tabulated values. TRY IT PROPERLY BEFORE YOU PAY Twenty-four of the calculators are free and stay free. The other twenty-eight unlock with a single payment that does not renew. Locked ones still open, still run, and still show their working, so you can see exactly what you would be buying. This is a calculator rather than a measurement instrument. It does not use the microphone and does not replace a sound level meter.