Looking for a calibrated audio solution for 3T and 7T fMRI?  We are proud to introduce BOLDfonic, an integrated, single-source solution for calibrated audio.  BOLDfonic delivers high-fidelity acoustic stimuli for fMRI while also attenuating scanner noise.

Our electro-dynamic driver technology uses the magnetic field of the MRI scanner to drive the headphone membranes. This results in powerful speakers with an excellent frequency response across a wide dynamic range. A novel USB sound processor with automated synchronous triggering capabilities and a fully–loaded amplifier system provide all the controls you need for rigorous multimodal EEG/fMRI studies.

BOLDfonic integrates perfectly with our LCD monitor system, eye tracker and the other Made for fMRI devices from our range.
Hear the Difference
You wouldn’t listen to the music on your iPhone with a stethoscope connected to its speaker…. Yet, most MRI-compatible headphones offer just that; audio piped to the participant down long, acoustic tubes. The result? Awful sound quality with restricted frequency response and restricted utility in research.
BOLDfonic includes everything you need for high-quality audio delivery in the MR:

A pair of electro-dynamic headphones. Various options are available to suit different types and sizes of headcoils.
A set of earphones to accommodate even the the tightest of headcoils
Fully–loaded amplifier system which provides all the controls you need for rigorous multimodal EEG/fMRI studies. Supports multiple signal sources and can drive two sets of headphones in parallel.
AudioFile USB sound processor with automated synchronous triggering capabilities
Desktop microphone for communication from the technologist. Ask us about our optional bi-directional communication feature which use the noise-cancelling Optoacoustics FORM-III participant microphone. Compact monitor speakers are included too, so you can always hear the same audio as your participant.

Better Audio Quality
BOLDfonic headphones utilize moving-coil transducers positioned in the headphone body, just like hi-fi headphones! As you can see illustrated in Figure 1, this results in excellent frequency response across a wide dynamic range.

Figure 1. Frequency response of BOLDfonic system headphones compared with standard acoustic audio system.

Though standard moving-coil transducers utilizing a magnet aren’t safe in an MRI room, the BOLDfonic headphone system features a unique electro-dynamic driver that utilizes the magnetic field of the MRI scanner to drive the headphone membrane. An additional piezoelectric driver can be fitted to some headphones, which enables them to be used outside the bore as well.
Reduced Gradient Noise
When compared to a standard scanner audio system, the circumaural, closed-back BOLDfonic headphones offer improved acoustic isolation from the gradient-noise of the MRI scanner. Acoustic attenuation is increased by at least 15dB over most of the audible range, as illustrated in Figure 2.

Where space permits, soft memory foam cushions can also be inserted between the head and contact points of the coil to provide even better isolation, reduce bone conduction and improve participant comfort.

Figure 2. Attenuation characteristics of BOLDfonic system headphones compared with standard acoustic audio system.

Easy to install
BOLDfonic headphones connect through the RF penetration panel using a pair of BNC bulkhead connectors. Two independent stereo channels maintain the high channel separation of the amplifiers. The filter/transformer set blocks DC levels, separates the ground of the RF cage from the ground of the audio system, and reduces unwanted RF-signals by about 85dB. Extra filters inside the scanner room reduce RF signals even further by about 90dB.

Figure 3. BOLDfonic system installation schematic.

A range of headphones to suit any MRI system
The circumaural, closed-back headphone is available in a number of sizes and cable routing arrangements to suit different headcoil designs (please refer to the table below). It offers superior gradient noise dampening compared to simple pneumatic, air tube solutions. Where space permits, soft, memory foam cushions can also be inserted between the head and contact points of the coil to provide even better isolation, reduce bone conduction and improve patient comfort.

A unique electro-dynamic driver uses the magnetic field of the MRI scanner to drive the headphone membrane. This results in powerful speakers with an excellent frequency response across a wide range. An additional piezoelectric driver can be fitted to some designs, which enables those headphones to be used outside the bore too.
A design for any headcoil
Headphones are available in a number of sizes and cable routing arrangements to suit different headcoil designs.

When there is insufficient space for headphones, an earbud-style earphone option can be used. This simple and effective solution places the headphone driver unit just outside the coil, and delivers the audio to the ear via a very short airtube and passive earbud, maintaining the best possible sound quality.

Headphones
Features
Size
Headcoil

HP VS 03

Headphones for all GE, Philips, & Siemens Head Coils.
Best electrodynamic performance, and passive damping, and is the slimmest electrodynamic option of any BOLDfonic headphone.
Designed for use with all GE and Philips head coils, and modern Siemens MRI (e.g. Prisma) with 20 channel head coil.
Headphones with excellent fitting accuracy. Slip-free, with minimal contact pressure for the participant. More than 30 dB passive gradient noise suppression over the entire EPI frequency range (500 Hz to 8000 Hz).
Dimensions: outer 80 x 105 mm; inner: 45 x 70 mm

HP AT 01 Insert Earphones.
In-ear air-tube headphones compatible with all head coils. External headphone drivers deliver 130 dB SPL through detachable air-tube with optimized length for a frequency response of up to 12 kHz.
Various different earplugs available. Ear defenders offer high passive dampening.
Works with any head coil. Headphone drivers must be located in the MRI scanner bore.

HP PI US
Ultra small on-ear piezo headphone for use in modern multi-channel head coils with a diameter down to 190mm. Also consider alternate HP AT 01 insert earphone (earbub) design.
Dimensions: outer 80x105mm, inner 45x70mm.
Works with any head coil. Works inside and outside the scanner.

HP M 01
Same electrodynamic driver system as of HP SI 01 or HP SC 01. Small headphones, optimized for use with children and NHP. Special version for pure passive dampening or matched, non MRI-compatible (MR Unsafe) headphones are available.
Dimensions: outer 60mm, inner 25mm.
Available for Siemens, Philips and GE scanners.

Earphones are the solution when space within the coil is limited
Some headcoils allow insufficient space to accommodate circumaural headphones. BOLDfonic earphones are a simple and elegant solution which places the headphone driver unit just outside the headcoil, and delivers the audio to the ear via a short airtube and passive earbud.

Electro-dynamic earphone drivers
The drivers use the same proven electrodynamic system technology as the standard BOLDfonic headphone. They’re safe to place within the bore or headcoil, so you can position them wherever is convenient. Ideally they should be reasonably close to to the ear, in order to keep the airtube length short. The drivers are connected to the control box either via the RF filter panel.
Airtube options
The airtube can be detached from the driver, so that the ear plugs can be inserted conveniently while outside the bore. Various lengths of airtube are available, depending on where you choose to place to drivers.

The sound pressure level at the driver is over 130dB, and decreases as the airtube length increases.

The frequency response is also a function of the tube length, for example 40Hz-12kHz for a 30cm tube or 40Hz-5kHz for an 80cm tube.
Earplug options
Various types of earplug are available.
Passive ear defenders
Passive ear defenders can be placed over the ears to reduce scanner noise. The ear defenders squash down well, taking up relatively little space.

Amplify your options
BOLDfonic stereo amplifiers are perfectly matched to the filter set and headphones; the design features multiple digital optical inputs to connect different signal sources. They are easy to operate for routine use, yet still offer sufficient flexibility and control of auditory stimuli for fMRI. The amplifier’s comprehensive design can drive two headphones, external speakers, and supports an optional noise-cancelling microphone for the participant. It even has a digital I/O interface to support direct integration with the MRI scanner.

Amplifier Feature
Parameter

Number of digital optical inputs
4 TOSLINK

Number of digital optical outputs
4 TOSLINK

Number of headphone outputs
2 stereo pairs

Channel separation (@ full load)
>85dB

Loudspeaker channels (stimulus & subject monitor)
4

Number of mixable channels
8+2

Built-in frequency generators
2

Built-in noise generators
2

Volume range
-120 – +30dB

Volume resolution
Arbitrary

Spectrum analyser
Yes

VU meter
Yes

Absolute SPL monitoring
Yes

Bi-directional communication
A compact desktop microphone sited in the console room can be combined with an optional noise-cancelling microphone mounted on the headcoil; this setup provides clear, simultaneous, bi-directional communication between the technologist and participant.

Synchronous auditory stimuli
Combining local solid-state storage of audio samples with an intelligent USB interface, the AudioFile sound processor makes it simple to synchronously and precisely mark the onset of an audio stream, with all the control you need for rigorous multimodal EEG/fMRI studies. The processor can be used in USB Audio mode, just like a standard USB soundcard, so that you can play any audio source available on the stimulus delivery computer, or as an independent playback device, which allows you to select and play WAV samples stored on the integrated AudioFile SD card.