Daily Calibration Fails With No-Response (NR) Errors

What's happening

Every day before testing, your system runs a check against the bio-acoustic simulator (BAS) to confirm the audiometer's output is still accurate — this daily check is part of what keeps your testing compliant with OSHA's occupational noise standard, 29 CFR 1910.95. "NR" means the check played a tone and got no response back from the BAS at all. "MR" means the opposite — it registered a button press that never happened. Both point to something in the connection between the audiometer and the BAS, not a problem with the subject or the test itself.

An occasional NR while things are warming up isn't unusual. But if it's failing repeatedly — several times in one morning — don't just cancel out and restart over and over. Work through the list below, and save or print the calibration log as you go. If the unit ends up needing service, that log is the clearest evidence of the actual pattern.

Try these in order

1. Unplug and replug the short cord connecting the audiometer to the BAS. This is a short cable that also carries power between the two units, so reseating it resets that connection — and clears a real share of these on its own.
2. Watch the BAS's response light while you do this. It should flash briefly when that cord is disconnected and reconnected, and light steady when the response button is pressed. If it doesn't react at all, note that — it matters for the steps below.
3. Check whether the failure is on one side only. If it's consistently one ear or one channel throwing NR, that points more toward the headphone cord or that same short BAS cord than toward the whole unit being bad.
4. Reseat the headphones and check the tension. Make sure the cushion sits flush and the headband is pulled all the way down. A cushion sitting slightly off can cause an intermittent failure that looks exactly like a connection problem.
5. Swap the short cord between the audiometer and BAS. This has turned out to be the single most common real fix. It's a 1/4-inch auxiliary patch cable, about 6 inches long — sometimes sold as a "guitar patch cord" — and the correct one has a single black band around the connector, not two (a two-band version is a different, powered/stereo type and won't work correctly here). It's a same-day option through any general electronics retailer, and it's worth trying before anything more involved.
6. If that doesn't fix it, try swapping the whole BAS unit if you have a spare, or flip which cord goes to which side. This helps separate a BAS fault from a fault further down the chain.
7. If the booth has a patch panel, bypass it. Disconnect the BAS/audiometer cabling and connect it directly rather than through the panel. A misaligned or faulty patch-panel connection has been the actual cause behind what looked like a dead unit more than once.
8. Don't assume a BAS swap alone fixed it. In more than one case, replacing the BAS entirely — even with a new unit — didn't resolve the failure, because the real fault turned out to be the short cord or, in one instance, stripped screws on the headphone connector that needed the transducer itself replaced. Keep watching the daily log for a few more days after any swap before calling it fixed.

If it still won't pass

Save a few days of the calibration log before you call us. It's the most useful thing you can hand over — it shows whether the failure is happening at one frequency or several, one side or both, and whether it's every test or intermittent.

If a subject's reference reading at one frequency looks unusually low or high but comes through completely consistently across repeated tests, that pattern can sometimes be worth factoring in going forward — but that's a decision we make together using your logged data, not something to adjust on your own in the field.

When to call us

• You're seeing actual threshold shifts on real tests, not just the daily check — stop testing and call rather than continuing to run people through a booth that's already failing its own calibration.
• Anyone reports crackling, popping, or a "short" sound in either ear.
• You've swapped the short cord and the headphone cords, checked both sides, and it's still failing.
• The BAS response light doesn't react at all to a plug/unplug or a button press.

We can usually get a loaner out the same day or next day if the unit needs to come in.