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 –

Screaming in Space

So you all know the phrase that none can hear you scream in space, after all its true, there are no air particles for the sound to vibrate which is how sound travels. But is there any sound, I mean can you see sound in space? The idea of an audio tour of space seems really bizarre for this reason alone, however the BBC have managed to make a program from it, so it must be possible right?

The Sun

The idea is that by observing movements of patches of varying gas densities on the sun, any differences can be linked to vibrations and can be recreated for us to listen to. The movements, however are very low in frequency, below what we could hear anyway (we can hear as low as 20 Hertz, which is 20 vibrations per second). In order to hear this, it has been sped up, which kind of seems like cheating a bit, but I guess it doesn’t mean it can’t exist just cause we can’t hear it!

This reminded me of one of my fellow students blog posts (at University of Salford) a few weeks ago about a very low frequency in space. This sound had a frequency of 0.0000001 Hertz, now that is what you call bass!

If you get a chance, have a watch of the BBC’s short clip (its only 3:40) and let me know what you think and what your favourite sounds are!


[1] Image of the sun –

Like the Guitar?

“What like the guitar?” is the usual response I get when I tell someone I’m studying acoustics at Uni; either that or, “so you make music?” or “what instrument do you play then?” or as someone on the tram said to me today “I guess people hear you coming then!”

First of all I would like to point out that I don’t blame people or think of them any less when they do ask these things, it’s a specialist area and I didn’t know what it was really either until a couple of years ago.

My interests originally began in audio where, even from a young age I loved the idea of anything technical or mechanical and even more so if it had electronics in it; so when I found out about an audio mixing desk, my mind was almost blown by the sheer number of space-like knobs, sliders and buttons! This fascination didn’t fade as I grew up, but instead shifted from wanting to know how operate a mixing desk, to wanting to know how to build a mixing desk.

When the time came to look for universities, I was looking at predominantly audio-based courses, of which Salford University was one of my options. I noticed that there was this thing called acoustics in several of the modules, which seemed interesting, and when combined with the appeals of MediaCityUK, was enough to persuade me to make Salford my first choice. As I started the course I grew more of an interest in acoustics and (although I still maintained an interest in the audio and electronics areas) this gradually became a more appealing area for me to pursue a career in, which has now put me where I am today.

So if it’s not about guitars or music, what is it about? Well, to quote the dictionary it is “the branch or physics that deals with sound and sound waves”, which practically speaking means a career for me as an acoustic consultant. There are 2 main aspects I am looking into as I aim to become an Acoustic Consultant, being Architectural Acoustics and Environmental Noise, which are both to do with the design of buildings in relation to how they will sound and the assessment/control of sound in areas respectively.

One main reason many people may not have necessarily heard of this is because it is relatively new (particularly the Environmental Noise aspect of it) to building regulations, so has not been so widely known before. Despite this, I believe acoustics is a great career to go into (obviously) as although it has been around for a long time, it is still developing greatly right now. Hopefully as I progress in my career more and more people will have heard of and understand acoustics.


What are your thoughts and opinions on the field of acoustics, have you ever heard of it before?