The document validates claims made about HDM® Pro hearing protection technology. It was tested using Sennheiser HD25 70Ω headphones to ensure reproduced sounds did not exceed regulatory noise limits. Claim 1 is that all sounds over 118dB are prevented. Claim 2 is sounds between 118-100dB are rapidly reduced to 100dB within 500ms. Claim 3 is the user's noise exposure does not exceed average limits set by the Noise at Work legislation, as validated by tests conducted over an 18 hour simulated day at the Institute of Sound and Vibration Research.

1. Validation of claims
made for
HDM®
Pro
Tests conducted with
HD25 70Ω
Headphones

2. The EU Regulations
EU Directive 2003/10/EC (Noise at
Work Act in the UK) states that
employees must not be subjected
to an impulse sound greater than
137dB* or an average noise dose
greater than 85dBA* over an 8
hour period or equivalent.
*From all sources

3. What does HDM®
Pro do?

4. Who have we consulted?
• UK Health and Safety Executive.
• ISVR at Southampton University.
• Hearing preservation charities.
• Unions.
• Insurance Companies.
• Potential end users in:
• Broadcast and live events
• Contact centres
• Industrial
• Emergency services
• Non-combat military

5. Claims for HDM®
Pro
1. Prevents all reproduced sound
over 118dB.
2. All reproduced sound between
118dB and 100dB is rapidly
reduced to 100dB.
3. Keeps all reproduced sound
below the levels defined by the
Noise at Work legislation.

6. Claim 1
Prevents all reproduced sound over 118dB.
This is a recording of the oscilloscope conducting the test

7. Claim 2
Reproduced sounds >100db* and <118dB*
are reduced in approximately 500 ms.
This is a recording of the oscilloscope conducting the test

8. Claim 3
Ensures that the users hearing dose from reproduced sound
does not exceed the regulated average for the relevant period
of time.
This challenging validation was contracted to Dr Mike Lower of
The Institute of Sound and Vibration Research at the University
of Southampton.
ISVR conducted a number of tests, including a simulated 18
hour day with exposure to different levels of reproduced sound.
HDM®
Pro monitored the reproduced sound exposure and
intervened when required to ensure that the noise dose was
below that specified for the period by the Noise at Work
legislation.
A copy of the ISVR report is available, on request, under an
NDA.

9. Validation of claims
made for
HDM®
Pro
Tests conducted with
HD25 70Ω
Headphones

10. Validation of claims
made for
HDM®
Pro
Tests conducted with
HD25 70Ω
Headphones