Headphones

And now for something completely different…

The difference between listening to music using speakers or a headphone is striking.

 

When listening to speakers:

When listening to a headphone, each ear will receive 1 and 1 channel only. No mixing, no delay, no indirect sound.

The latter means that the room acoustics are eliminated.

More details can be found here.

Crossfeed

Using DSP one can emulate listening to speakers over a headphone by mixing the channels a bit, adding delay and even emulate the room. This is called the HRTF (Head Related Transfer Function) or crossfeed.

Benjamin B. Bauer was one of the pioneers.
A famous article by him: Stereophonic Earphones and Binaural Loudspeakers.
JAES Volume 9 Number 2 pp. 148-151; April 1961.

 

Your media player might have one or there is a plug-in.

A VST plug-in and a lot more about headphones can be found here: BlogOhl

ToneBoosters Isone EUR 20.00

  • Zero latency processing
  • Low CPU load
  • Sample rate support up to 384 kHz
  • Customisable HRTF's
  • Customisable listening room and distance
  • Wide variety of loudspeaker models
  • Support for 64 bits audio data processing.

MathAudio Headphone EQ VST $60.00

A graphic equalizer and crossfeed.

You can define 9 bands by choosing a certain frequency, apply the desired gain (plus or minus) and the width of the band.

A small band allows you to compensate for resonances.

A wide band allows you to compensate for e.g. a warm midrange.

All processing is done in 64 bits.
It support sample rates from 44 to 352 kHz.

Added 4/2014

HeaDSPeaker 5.1 Headphone Surround System

HeaDSPeaker system consists of two main parts: tracking sensors and a DSP unit.

Tracking sensors should be attached to your existing headphones.

The provided DSP unit processes the multichannel input signal and produces a dynamically auralized stereo signal for the headphones.

 

HeaDSPeaker is capable of decoding 5.0 multichannel signal from 2.0 stereo sources (the analog output of modern game consoles, for example).

It can also act as a 5.1 or 7.1 USB sound device when connected to a PC or Macintosh computer.

In addition the HeaDSPeaker Home version can decode Dolby Digital and DTS encoded sound from optical S/PDIF.

Connections:

  • Optical S/PDIF (Dolby Digital 5.1 / DTS 5.1 / 2.0 PCM) [HeaDSPeaker Home]
  • USB (7.1PCM / 5.1 PCM / 2.0 PCM)
  • Analog 3.5mm stereo (2 channels stereo / 5 channel DSP-Logic active matrix decoding)
  • 3.5mm stereo plug for binaural multichannel headphone output
  • 3.5mm stereo plug for head-tracker (included) input

Smyth Realiser A8 USD 3,360.00  

Includes Headtracking and In ear measurement



Bundled with a Stax SR-202

Sound Performance Lab - Phonitor € 1649,-

 

Manufacturers description:

In addition to its standard monitoring functions the Phonitor offers new controls such as “Crossfeed“, “Speaker Angle“ and “Center Level“. These are the essential parameters that create the width, balance and overall space within a listening field and how we recognize them coming from the loudspeaker. Crossfeed simulates the frequency dependent interaural level differences from both channels. Speaker Angle determines the stereo width caused by frequency dependent interaural time differences. Center Level regulates the balance between phantom centre and L/R stereo signals.

 

A review by Sound on Sound

Measurements

Headroom

HeadRoom is a website selling headphones.

They havemeasurements of a lot of headphones.
They explain what these measurements indicate and enables you to compare up to four models on frequency response, distortion, impedance, isolation and square wave response.
This won't tell you how it will sound but gives you a nice indication.

This graph tells you that Shure SE530 is louder at the low frequencies than Etymotic ER-4S.

It also rolled-off the highs much more so it will probably sound bass heavy.

 

Both in-ear models offer a better sound isolation than the open Sennheiser HD800

 

Both in-ears produces a lot of harmonics compared with the HD800.

 

Innerfidelity

Beside a subjective listening test, Tyll Hertsens  always publish measurements for the headphone at test.

His methods for measuring are explained here.

A massive PDF with a lot of measurements

 

Goldenears.net

The way headphones are measured is documented here.

Effin'Ringin'

A critical forum of headphones addicts.

A little bit of Latin


Yes, Latin helps in case of headphones.

 

What kind of headphone do you have?
Oh, a circumaural one.
What the hell is that?
That’s one surrounding the pinnae.

 

Circumaural headphones surround the ear.

Sennheiser HD 800

 

Supra-aural headphones sit on top of the ears

Sennheiser HD 414

 

Intra-aural ends our Latin lesson.
These are placed in the ear.

Earbuds are placed directly outside the ear canal

 

B&O A8


IEM (In Ear Monitor).are inserted in the ear canal

Etymotic HF 5

 

You might conjecture up the Latin your self, one sitting on top of your head

Jecklin Float

Custom fit

You can buy custom molded in-ear monitors.
You go to an audiologist,
He makes an impression of your ear,
Send it to the factory,
Wait until they ship your custom-fit IEM.
Oh yeah, you have to pay a substantial amount of money too.

 

Why not rolling your own!

 

Take a pair of Sonomax Eers headphones.

Put them in your ears while attached to the thingy below.

Pull the trigger and don’t move your jaw for 5 minutes and you have your custom mold.

Source: eerscustom fit earphones

Connecting

Jack

Normally a headphone is connected with a jack.
As a jack is tip, ring, sleeve you have three wires, the signal for the left and right channel and a common ground for both drivers.

Symmetrical

An alternative is to connect the headphone with 4 wires, a separate + and – for each driver.
This is exactly how we connect our speakers  to an amp but for some reason it is often called a “balanced” connection in the headphone world.

A true balanced connection is using 2 signal wires, one carrying the signal and the other the inverse and a third for the earth.

 

To do so, you need to rewire the headphone and need a headphone amp with XLR output.

 

Headroom BUDA balanced headphone amp

 

Sennheiser’s HDVD 800 DAC/Headphone amp

The HDVD 800 has symmetrical outputs for the headphone.

 

IR

Infrared is almost free of interference.
The downside is that sender and receiver must literally see each other.
Infrared is in general limited to 10 m.

RF

Wireless headphones often use a RF (Radio Frequency) transmitter.
The advantage is its long range (up to 100 m) and sender and receiver don’t have to be in the same room like in case of IR.
RF transmitters often use the 2.4 MHz  band.
This might cause interference.

Bluetooth

Bluetooth is a popular protocol to connect a headphone wireless because its power consumption is low.
This crucial as beside the Bluetooth receiver the battery also powers the built-in DAC and amp.


The limited bandwidth of Bluetooth makes it impossible to send lossless audio to the headphone.
Sound quality also depends on the quality of the DAC and amp used inside the headphone.

 

As the signal received is digital, it is possible to apply all kind of DSP.
ANC (Active Noise Cancelling) is one of them.
The Parrot Zik comes with an app (Android/Apple) for the smartphone allowing you to apply all kind of DSP.

 

Parrot Concert Hall DSP

WiFi

As WiFi is a very popular protocol and is not handicapped by limited bandwidth and range like Bluetooth it looks like the ideal protocol to connect a headphone wireless.
Unfortunately, power consumption is high compared with Bluetooth resulting in a limited battery live.
The Koss Striva is the only WiFi enabled headphone known to me.

References