The speakers that produce the lowest bass are tactile transducers — they typically produce frequencies in the 0.5 – 20 Hz range. Tactile sound is not perceived through the ears — it perceived through the body. Most subwoofers are incapable of producing audio in this range.

A good tactile transducer to start with is $150, entry-level Clark Synthesis Silver Edition (TST239) — it provides ample sub-frequency bass for the home user.

The Details

Tactile sound is the sensation of sound transmitted directly to the human body by contact, rather than by sound waves through the ears (tympanic sensation).

More specifically, it is sound perceived through bone conduction, through muscles and deep tissue, and via skin sensation. We perceive the vibrations through our haptic senses which include both kinesthetic (muscle) and touch (cutaneous) senses. We feel both inaudible (infrasonic frequencies) and audible frequencies. Thus, tactile sound is not just brute rumbles and shock waves.

Tactile sound can be perceived in high fidelity up to the mid-range frequencies. According to NASA research we perceive 0 to 1 kHz through the sense of touch, 0 to 3 kHz through kinesthesia (the sense of the relative position of neighboring parts of the body), and 0.20 kHz to 20 kHz through our ears. Note there’s an overlap — we can hear the range of 0.20 kHz to 3 kHz both with our ears and through other parts of our body. Also, some hearing-impaired individual can hear sounds up to 5 kHz through their skin.

Tactile sound is a sensation that many seek out. People often buy expensive subwoofers to achieve deep bass effects. In this pursuit, subwoofers are often pushed past recommend levels, resulting in damaged equipment, muddied sound fields, and disturbed neighbors. Typically, subwoofers not produce tactile sound very well. They are designed to transmit low frequency sound through the air, and they don’t usually produce bass below 25 – 30Hz. Correctly installed and enclosed subwoofers can producer lower and louder deep bass, but they will not produce the same level of tactile vibrations.

So what kind of device produces tactile sound? Tactile transducers, or electro-mechanical devices that are built specifically to vibrate objects. They are very similar to a loudspeaker woofer driver minus the cone.

There are two basic flavors of transducer: inertial shakers and linear actuators. Let’s take a look at the differences between the two:

Inertial Shakers

Inertial Shakers operate by shaking a mass in an enclosed housing. The resulting vibrations are transferred to an attached object, like the wooden crossbeam of a couch, for example. Usually, shakers are bolted directed to an object.

Companies that make Inertial Shakers include: Clark Synthesis, Aura Sound, Earthquake Audio, Buttkicker and Sonic Immersion Technologies. These devices vary widely in price — some produce a simple shaking effect, some produce high-fidelity sounds that compliment to a stereo system or home theater (such as those offered by Clark Synthesis, my personal favorites).

A good tactile transducer to start with is $150, entry-level Clark Synthesis Silver Edition (TST239). It will produce solid definition to drum hits, or shake your fillings loose if you so desire. The transducer can be installed in less than an hour. It took me about 45 minutes to bolt it to the bottom of my couch, using the parts provided with the transducer. In my test installation, I removed the fabric from the button of a couch, and bolted the transducer to a crossbeam underneath. Once installed, the entire couch functions as a bass speaker.

But wait, we need to power the tactile transducer! Clark Synthesis sells a $350 customized tactile amplifier to do this, but you can actually use any amplifier that outputs at least 100 watts (check the Clark Synthesis documentation for more info). Well, Cambridge Audio makes good amplifiers, but their entry-level models start at $330. We can instead use an AudioSource amplifier. This is a 2-channel 100-watt (50 watts x 2) power amplifier, which can be purchased for under $100. This amplifier is well-reviewed —  111 reviewers on Amazon gave it an average of 4 out of 5 stars. You attach your amplifier to the tactile transducer using standard speaker cables. You then connect the amplifier to the Sub Out connector on your receiver.

Linear Actuators

Linear Actuators are transducers that push against a hard surface. They apply a force directly to an object, in contrast to Inertial Shakers which vibrate themselves, and then transmit that vibration into another object. Commercially available Linear Actuators usually replace the feet of a chair. They operate by pushing against the floor, and directly lifting and dropping a chair. They tend to be more expensive that Inertial Shakers, and they can be only installed under chairs — they can’t be installed under a floor or in a swimming pool like the shakers above.

Companies that offer Linear Actuator include: Crowson Technology and d-Box Technologies.

See also: The Tactile Transducer FAQ

The post The Speakers With The Deepest Bass: Tactile Transducers appeared first on Reactual.

H2O Audio Surge 2G Waterproof Headphones

H2o Audio, an innovator in developing underwater accessories, has recently released their improved Surge 2G waterproof headphones. These are the headphones used and endorsed by Olympic swimmer Michael Phelps. They are 100% waterproof for underwater submersion up to 12 feet and can be rinsed after a strenuous workout. Five sets of varying sized rubber tips are provided to find the right fit. According to iLounge, these earbuds form a more complete seal in the ear than other headphones they’ve tested. Also compared to other underwater options, the H2o Audio Surge 2G offers an unparalleled sound with a sound-isolating fit and bass amplified neodymium drivers to provide a balanced quality both above and below the water.

The plug is designed to fit into H2O Audio’s waterproof armbands and cases so is only compatible with the iPhone 3G and all iPod models. For other Mp3s or the original iPhone you’ll need a case with a pass-through port or an adapter.

The H2o Audio Surge 2G waterproof headphones retail for $49.99, but are currently on sale at Amazon for $25.59. Comes with a waterproof carrying case. Also offered is a model with a built-in waterproof microphone for around $50.00 here.

Aquapac Waterproof Headphones

The Aquapac waterproof headphones that operate at an underwater depth of 30 feet, but are not advised for use beyond 10 feet due to pressure on the ear. Underwater headphone testers at iLounge gave the Aquapacs a B rating. They were impressed by the sound quality both above and below the water. The silicone tips create a seal in the ear to prevent water from getting in, though the one downside to the Aquapacs are that they only come with one size tips that will fit average sized ears.

The Aquapac waterproof headphones come with a buoy and keychain cord keeper.

You can get them on Amazon for about $47.

Audio Bone Waterproof Headphones

The Audio Bone headphones use bone conduction technology which allow the user to wear the headphones on the outside of their ears. Since we hear differently while submerged in water, this technology completely bypasses the ear drum by converting sound waves into vibrations. There are pros and cons to this type of headphone and after reading reviews by those who have tried them, people either love them or hate them.

One of the cons is the price. The audio bone headphones retail for $189.00. However, these headphones do transfer well to all activities, such as cycling or even listening at work, since it allows you to still be able to hear other things going on around you. Another con is that bone conduction is a less efficient way for us to hear, therefore your iPod or Mp3 will generally need to be on the highest volume setting which can cause the battery to drain faster. Some users report a muffled sound quality, while others like that they can still hear outside noise. Your personal preference would depend upon the intended use. Also, many people don’t like the feel of earbuds so the Audio Bones are a perfect match for them. You can read a full review at the Gadgeteer and CrunchGear.

The Audio Bone Waterproof Headphones are currently on sale at Amazon

Budget Pick: H2O Audio Flex Underwater Headphones

These Flex headphones are the newest entry from H2O Audio and our budget pick for a waterproof headphone. These would be a good option for someone who needs waterproof headphones from time to time, perhaps for sweaty workouts, occasional laps in the pool, or just lying in the bath. They are submersible up to 3 feet underwater. Amazon reviewers complained about the fit with these headphones, though they do come with 3 bud sizes. As one reviewer pointed out, be sure to wipe out your ear so that it’s dry before inserting the buds. This will help create a stronger seal and they won’t slip out as easily. Also, wear the wires on your back and insert the headphones from behind your neck. The sound is of good quality and is well-balanced. Those who prefer a strong bass won’t get it here, but again, the price is key. For a full review on the H2O Audio Flex click here.

The H2O Audio Flex underwater headphones come in a choice of 5 cool colors and are on sale at Amazon for $19.41.

Waterproof iPods Cases

If you spend a lot of time in the water, you may want to consider investing in a fully waterproof system. Companies such as H2oFriendly and Swimman will waterproof an iPod shuffle from the inside out so you can take it right into the water without use of a bulky case. User reviews for both of these systems are excellent both for quality and for ease of use. H2OFriendly offers a 1 year waterproof warranty and you can purchase just the 4th generation 2 GB iPod shuffle or a complete system which includes Velcro securing straps that clip onto goggles and underwater headphones, as well as the original iPod shuffle packaging.

The H2OFriendly Swim System sells for $169.95 on Amazon. Or just the silver waterproof iPod goes for $143.95 on Amazon. You can also order straight from the company’s website if you’d like a choice of iPod colors: green, orange, blue, silver, or pink.

Swimman has an excellent reputation among swimmers and they are currently waterproofing 3rd generation iPod shuffles. At $250.00, their system is more than the H2oFriendly, but they do include a waterproof control adapter and their underwater headphone set boasts superior sound quality similar to top-of-the-line non-waterproof headphones. To purchase Swimman order directly from their website. You can also purchase their headphone set separately for $100.00 here.

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