Denman Audio

Audio technology has come a long way since the early 1900’s and this can be seen by the size of the Denman horn, which is a massive 27ft long! When this horn was built, it produced incredible quality audio and it still does considering how long ago it was built. Even though it was built all that time ago when sound equipment wasn’t great, just a little knowledge of some basic acoustic principles meant that this horn could be made. Nowadays we have many ways in which we create high quality audio, particularly in  smaller and smaller enclosures, but the same basic principles used back in the 1930s are still in practice.

Horn loudspeakers work the way they do because they create a greater pressure around the speaker cone, which is the same effect of putting your guitar amp in a corner. When a sound source is placed on the floor, the area in which sound can propagate into is halved (assuming it propagates in all directions evenly and cannot propagate into the ground), meaning that the sound  pressure is doubled. This effect happens again when you place it against a wall and again when in a corner, hence if you want the best response (particularly bass) from your guitar amp, then stick it in a corner. As the horn surrounds the speaker, the sound pressure in massively increased and sound level becomes greater.

The gradual flaring out of the horn is used to slowly match the pressure around the speaker to that of the natural environment, reducing unpleasant audible effects that this could cause otherwise. As length of the horn increases, the  low frequency response increases, due to the longer wavelength of low frequencies (a greater distance between their sound compressions).

These methods can still be used today, but are altered into a smaller context, or are implemented in a different way, often taking advantage of the resonant frequency of a speaker enclosure, in an attempt to boost the signal. Nowadays a more common method is use of a vented box (a speaker with a hole in the front). Even though we no longer have to have a 27ft horn in our house to get high quality audio, there are still many things we can learn and use from audio methods of the past like the Denman horn.

What do you think of this, would you still want a music player in your house if it was the size of the Denman horn?


[1] BBC News Article –


Beats by Apple

So those who know me will know that I like my tech, especially that which has a shiny apple on the back of it, which meant I was interested to read this week about Apple’s latest purchase. If you hadn’t already heard, Apple are currently in the process of buying Beats, the headphone brand that Dr Dre is co-founder of for $3.2bn. Generally speaking, this didn’t really surprise me, but deep down I kind of wish it had shocked me more… Let me explain.


Beats are a brand that can really split opinion (like Apple) and this opinion massively depends on who you ask. Ask most people on the morning commute and I imagine that most of them will like, or possibly own Beats, but ask any audio geek or tech fan and 9 times out of 10 they will probably have the opposite opinion. The brand is one that is very desirable and aesthetic based which, although is not a bad thing, can mean that you pay extra for the letter ‘b’ on each ear ‘can’. If this is compared to a brand like Bose for example, whose business strap line is ‘Better sound through research’, vast differences can easily be seen.

Bose (or Sennheiser for example) are both tech companies, based to create products with cutting edge tech that sounds great, whereas Beats do that with more of an emphasis on image (this is starting to remind me about the whole Apple vs Microsoft debate!). Headphones naturally are a more desirable accessory to own (as written about by a blog from Trevor Cox when comparing public perceptions for headphones vs loudspeakers), so I guess part of this comparison between companies could be to do with the background of the company.

Infograph of most common words associated with Headphones and Loudspeakers. Words nearer top related more to loudspeakers and vice versa. Words on right more commonly used than those on left. Credit Prof Trevor Cox

Infograph of most common words associated with Headphones and Loudspeakers. Words nearer top related more to loudspeakers and vice versa. Words on right more commonly used than those on left. Credit Prof Trevor Cox

One major conflict of agreement will come when the quality of audio produced by Beats headphones is mentioned, some love it, some say it is awful. For me, I would prefer a pair of headphones by a tech company, but I can see that Beats do make some good sound. The main advantage to Beats audio quality is that there is bass and lots of it. The target market for these is primarily younger who listen to bassier music, which makes sense. Bass tones have the effect of making the user feel like that the sound is more immersive. This is to do with the wavelengths of bass sounds being bigger, hence it physically surrounding the listener more meaning they can feel the sound, not only through their ears. However, bass is not the be all and end all of audio quality; there are many more things to look out for in a good set of headphones (Comfort, Clarity, Sound Isolation, Frequency range, Price/Value for money…).

So if the quality is not so good, why do people buy them? To be honest, most people may not be able to notice the difference, or may not really care. One of my course mates wrote an interesting blog this week on whether we really care about the quality of our music, or whether we just go for convenience which I would recommend if you get a chance. One other main factor is again about appearance, if you’re going to spend £100-200 on some headphones, you want them to be noticed!

To me, Apple is a company of quality, yes with a big emphasis on image, but mainly focused on quality (more generally speaking and not when it came to audio!). Hence, when I saw they were buying Beats, I was kind of disappointed that they had opted for image over top end quality. Saying this though I can’t imagine them ever having bought a company like Bose or Sennheiser. When it come to brands (particularly those that make tech) people really buy into products, which is a factor that makes a huge difference (e.g. opinions of peers etc). Because of this I can imagine plenty of you will have different opinions to me! I would love to hear these if you want to comment below, alternatively click below which of the two options you’d choose!


[1] BBC News article –

20/20 Audition

So you know what 20/20 vision is, it’s when you have perfect vision. But what is the equivalent for your ears? Well I think it should be called 20/20 audition; let me explain why…

20/20 vision is defined as how well you can see at 20 feet away, with 20/20 being what you should be able to see with clarity. However if you have 20/100 vision, you have to be 20 feet away to see something that someone with perfect sight can see at 100 feet away. “So what does that have to do with sound” I hear you cry, “last time I checked you can’t see sound!”. If you said that, you would be right, however the 20/20 part is to do with how we measure hearing.

Hearing is measured by how quiet you can hear sound (your hearing threshold) at different frequencies. Because sound is created by vibrations, we measure frequency by the number of vibrations per second (which we call hertz or Hz for short). 20Hz is the lowest we can hear, which literally means 20 vibrations per second and 20,000Hz is the highest we can hear, which is 20,000 vibrations per second. For hearing tests, a sound of a known frequency is played and the listener adjusts it to the quietest point at which they can only just hear it. This level is then compared to what the level should be for perfect hearing and the difference is the hearing loss at that frequency.

Hearing Loss

As we become older, we lose sensitivity in our ears, particularly at higher and lower frequencies, meaning the range that we can hear is reduced. As perfect hearing goes from 20Hz to 20kHz (20,000Hz), this is why I think it should be called 20/20 audition (audition is just another word for hearing). From what I could seem to find online, there wasn’t a term for perfect hearing like there is for sight, only “normal hearing”, which seems a bit boring to me. Do you agree with me, or if not what do you think perfect hearing should be called?


[1] What is 20/20 vision? –

[2] What is normal hearing? –

[3] How is hearing measured? –

Hearing for the First Time

You may have seen this video during the week, it’s a lovely story of a lady called Joanne Milne (40) who was deaf from birth and her hearing was restored with a cochlear implant. This video shot by her Mum shows the moments when she hears for the first time, in tears as the nurse recalls the days of the week to her. Watching this made me appreciate how much of a difference my ears make to the world I experience everyday. I mean some people (including myself) have recently been talking about the sounds of F1 and how they don’t sound as nice as previously, but imagine that with no sound at all and I think it really puts it into perspective!

It is said that if you have shortfalls in one aspect of life then you more than make up for it in another and this is certainly true in this case! I mean think about it, she’s been deaf for her whole life and partially blind also and as soon as she can hear she can start talking! This is the power of lip reading, something she has very clearly mastered over her life and has been able to work out a whole language even though she has never heard it. I bet none of us could go abroad, having never learnt their language and then pick it up just by lip reading!

Someone who has been through the same thing is a lady called Kate Locke, who has written a blog as she has gone through the process of getting a cochlear implant. If the video interested you then it is definitely something to check out! She writes very well about what a cochlear implant is and how it works, which I am going to try and briefly summarise here!

Cochlea Implant

There are 3 parts to the ear: outer, middle and inner; Joanne’s hearing condition was called sensorineural hearing loss, which is damage to the inner ear. Damage to the outer or middle ear is easier to repair (i.e. perforated ear drum) however the inner ear is the part that sends electrical impulses to the brain which is what makes it harder to heal. Other types of inner ear damage include Presbycusis (old age) and Noise Induced Hearing Loss.

Whereas hearing aids work to simply amplify sound, a cochlear implant is different in that attempts to instead mimic the natural hearing system. It first of all captures sound using a small microphone, similar to in a hearing aid, but instead of amplifying it, the sound is converted into a digital code and then into electrical impulses. These impulses then travel down into the ear and are passed through an array of electrodes in the cochlear that stimulate it. Normally, in a functioning ear, there are tiny hair cells in the cochlear, so that when the sound wave causes them to move, an electrical signal is sent to the brain; however in this case the electrodes trigger this instead as these hair cells are either lost or damaged.

As an aside, this is why you get a ringing in your ear when loud noises are heard over a prolonged period of time. As sound enters the ear, the hair cells are bent, sending signals to the brain, however when this is prolonged the hairs stay bent causing the brain to think of this as a constant noise. Eventually the hairs return to their natural position, causing the ringing to stop, although repeated exposure will eventually cause lasting damage (i.e. noise induced hearing loss or tinitus).

There are many aspects of life where sound is the best part and many others where we just take it for granted. What was your reaction to the video and what sounds would you miss most if you couldn’t hear?


[1] News Article containing the video –

[2] Kate Locke’s Blog –

[3] How Cochlear Implants work –

Is Formula 1 too quiet?

An interesting blog from a course mate about the new F1 engines. I understand when people in the crowd say that it is better for watching and not needed earplugs, however the sound just doesn’t seem quite right! As I watched the video, the cars seemed like they were going slower in the second clip, but hey that’s psychoacoustics for you!

Notes from an Acoustician

Did you watch the Melbourne Grand Prix last weekend? It was the first race of 2014 Formula 1 season. This year has seen the most rule changes for a generation, but the most controversial was the sound of the engines. Since the late 70’s F1 fans have been used to the high pitched screech of the engines as the cars fly by. This year, however, with the new regulations regarding the hybrid engine systems, smaller engine size and the reintroduction of the turbo, the the sound of the engine is very different. Watch this video to see what I mean. It compares the engine sounds of the Melbourne Grand Prix in 2013 to 2014.

As you can see, the new cars are much quieter and much lower in pitch. If you notice, the guy sat just in from of the camera in 2013 clip is wearing ear defenders. In 2014 there is no…

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Why wear ear plugs?????

Interesting article from a friend regarding why we need to be careful of increased noise levels nowadays


As a musician, gig goer and acoustician noise levels appear frequently in my life, but what is so important about noise levels?

For example, ever go on a night out and wake up in the morning with ringing in your ears? If yes, then this is a short-term case of tinnitus, and is caused from the loud music and your friends shouting down your ears. How? In the inner ear, the hair cells are triggered by a sound wave entering the ear, (these hair cells convert the vibrations into an electrical pulse, that is sent to the brain) when there are exceptionally loud noises, these hair cells become damaged, and mistakenly send auditory information to the brain. In the case of a night out, I am sure you are aware the ringing is temporary and subsides after a few hours. This is because the damaged hair cells can repair themselves…

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Pain in the Neck

I saw this tweet today saying that Motorola (owned by Google) has put in a patent for a neck tattoo that also acts as a noise-cancelling microphone… Now that takes wearable technology to a whole new level! The device (which I’m guessing will be very small!) is a small electronic chip that will be somehow tattooed into the neck and will measure vibrations. This is an interesting concept and is something that straightaway comes with many questions like “how will it work?” and “what will it do?” etc etc. This is also something I’m sure that will come with plenty of strong opinions, some supporting it and some against it.

The basis of it is a throat microphone (not a new concept) but one that is not removable, which should be useful for phone conversations, picking up the vibrations straight from the throat and eliminating any other unwanted background noise (it works on the same basis as active noise-cancelling headphones). Particular uses would come in busy areas where there is a lot of background noise; although it does have the increased potential to make you look crazy, like you’re talking to yourself!

One other aspect of it that seems to have been highlighted is that of a lie detector, as explained in the Telegraph article linked in the tweet above:

Equipped with a display that lights up under certain conditions, “the electronic skin tattoo can further include a galvanic skin response detector to detect skin resistance of a user.”

The patent continues: “It is contemplated that a user may be nervous or engaging in speaking falsehoods may exhibit different galvanic skin response than a more confident, truth telling individual.”

This to me does not seem a logical idea, as who is going to want to let people know when they are lying? And besides, I’m sure there is some kind of law against forcing people on the Jeremy Kyle show into getting tattoos they don’t want! Maybe Google have thought of some clever reason for it I haven’t thought of?! Apart from that there are other downsides, like the obvious one of having to have a tattoo on your neck you may not have necessarily wanted otherwise.

This is not Google’s first attempt at wearable, or ingestible technology and I’m sure it won’t be their last either, as somehow I can see more and more technology being made more ‘convenient’ and discrete, especially with the development of Google Glass. Some people are willing to give any new technology a go in the name of development, but for me this just seems one step too far into the crazy. What do you think abut wearable technology, is it something you would try?