View source for Sennheiser HDA300 specifications

==Description==
The HDA 300 is a pair of closed dynamic headphones designed for use with audiometers. It is used in aural-acoustical analysis and measurements for ENT doctors, educational facilities and research & health centers. The HDA 300 sound profile is based on the well known HDA 200 audiometric reference headphones, which is the standard for high frequency measurements in Audiometry since over 20 years, combined and enriched by the latest standards in terms of materials and design. 
*High passive ambient noise attenuation
*Equipped with two mono plugs
*Soft, replaceable ear pads
*Single-sided cable

{| class="wikitable"
! Specification
! Value
|-
| Connector
| 2 Mono-Jacks; Green: -L, yellow: +L, red: +R, blue: -R
|-
| Frequency response (Headphones)
| 20 Hz - 20,000 Hz
|-
| Characteristic SPL
| 117dB at 1kHz, 0.5V
|-
| Contact pressure
| 8.8N ± 0.5N
|-
| Ear coupling
| circumaural
|-
| Connection cable
| approx. 2.2m
|-
| Transducer principle
| dynamic, closed
|-
| Weight
| incl. cable: 490 g
|-
| Nominal impedance
| 23 Ohm
|-
| Load rating
| 500 mW
|-
| Max. Input voltage
| 3.5 V, < 10 min
|}