Recording near the Sea

Recording the sea presents its own challenges, but recording something other than the sea while near the sea presents a very difficult challenge – how to avoid varying degrees of broadband noise over everything? This was one of many facets of recording seal vocals that I had to work through and I thought it might be worth sharing a few things I learned in the process.

The first consideration has to be the weather. We had a southerly storm come through Wellington earlier this week and I heard the surf report that morning on the radio: “there’s currently a one metre surf but by lunchtime it will be 3-5 metres, and round Cape Palliser it will be 8 metres” HOLY CRAP!!!!

Here’s some video/sound of a beach about 1km up the road from the seal colony and when you watch it, imagine that same beach with an 8m swell!

So how did I know it was going to be such a gentle swell as per the video, and not 8m? Well part good luck and part good management: I told a friend of mine about my planned trip and he sent me a link to Swell Map a site often used by surfers amongst others… Now I obviously knew the tides are predictable and that was the information that I primarily thought I needed, as I figured if the tide is out the waves are further away from where I’ll be recording… Here is a copy of the swellmap for the weekend I was at Cape Palliser:

Swell Map

So Friday was raining when I left town, but I knew from the weather forecast that the storm was to clear Friday night & the weekend was meant to be pretty settled. So I arrived there Friday afternoon and from the bottom tide chart I noted that low tide was 5.40am Saturday morning, so I paced myself to get up as early as possible Saturday & Sunday morning. Saturday morning I made it to the seal colony as dawn was just breaking; there is a lighthouse at Cape Palliser and I noticed it was still shining when I arrived. I also noticed the waves at that beach in the video were pretty small & further out the sea was pretty flat, and if you look at that swell map again you can see that it predicts what I describe in the middle chart, with a swell less than 1m. I was mightily impressed by the swell map – I knew tides were predictable but I printed out the swell map above almost a week before my trip; how do they know? But also note, they predict the wave periodicity, wind direction and wave front complexity!!

Ok so if factor 1 for recording near the sea is weather and factor 2 is tides/swell, then factor 3 is microphone choice. Friends of mine own Sennheiser 816 microphones and I’v used them a few times when doing vehicle recordings, to capture the maximum approach and away of vehicles as the 816 is a long, directional shotgun mic with far greater ‘reach’ than any fo the shorter shotgun mcis that I’ve used… Last year a secondhand Sennheiser MKH70 mic appeared on local online forum and as I knew it was the new version of the 816 I bought it. And if you’re ever shopping for mics, it really pays to be patient and try for second hand – to give you some idea of the saving I made the MKH70 retails for US$2,975 – I paid US$800 for this one and it came with a Rycote and fluffy! But other than a few vehicle recordings I had never had a real reason to use it much, but the more I thought about it the more I realised the MKH70 was the perfect mic for the seal recording.

MKH70

A friend who owns an 816 advised me to be careful when using the MKH70 with regards to the rear of the microphone. The important aspect with this advice is that these mics are good at rejecting the side information (ie sound at 45 degrees from the mic) but the rear of the mic is vulnerable, so eg if the front of the mic is pointed at a seal but the rear of the mic is pointed at the sea, then the results won’t be so good. So I was constantly careful to keep the front of the Rycote ‘on mic’ at the seals while the rear was pointed either at the ground or at the sky ie NOT horizontal with the rear pointed towards the sea! The image below is a typical polar response of a shotgun mic:

shotgun polar

And heres the polar response for the MKH70:

MKH70 polar

Apart from the mic choice, I also for the first time ever used a boom for the seal recording. And wow! Did I sleep well Saturday night after spending 5 hours wrangling a boom while climbing all over the rocks!

mic + boom

My primary motive for using a boom was safety – I knew I wanted to get the mic close to the seals, but I wasn’t keen on getting bitten for obvious reasons. In tests that I did, I noticed that seals rarely took any notice of my presence until I was within a few metres of them, and having observed how fast they can move I decided to use a boom, and generally speaking I had the boom on full extention which put the mic 3m away from me. So I would be in record (ALWAYS be in record!) and would slowly edge into the seals comfort zone, and often times the mic would be within half a meter before it took any notice!

One aspect of recording with the MKH70 that messed with my senses was the idea of recording with a mono mic. When I was slowly, carefully moving around through the rocks recording I would be monitoring through my headphones but as the MKH70 is mono I lost my sense of direction. A few times I would hear an interesting call in the distance, and had to take my headphones off and use my ears to locate where it actually was coming from! The things you take for granted!

The last aspect of recording by the sea was that I discovered how important proximity & masking can be. The conclusion I came to with this was that it was acoustically possible to hide from the direct sound of the sea! I noticed this more as it got towards lunch time and the tide was coming in, so the waves & waterlap became more pronounced, but monitoring through headphones I noticed it was almost like line of sight: if I was down amongst rocks the sound of the sea was considerably muffled! And this aspect accounts for some of the best recordings I got of the seals – sometimes the seals would not retreat to the sea but instead would move into one of the labyrinth of caves & tunnels underneath the rocks… And of course my microphone tended to follow them into some of these contained spaces, but it was amazing to hear the ambient background shift from being present, to being muffled (behind rocks) to being totally subdued down underneath the rocks! if someone had suggested this phenomena I would have been sceptical but the results speak for themselves – there are more than a few seal vocals that almost sound like they were recorded in an ADR studio!

 

SEAL VOCALS LITE preview by timprebble

 

7 Responses to Recording near the Sea

  1. mny says:

    Great recordings and thanks for sharing.
    Never realized how funny seals can sound….I think i would have messed up most of the recordings because of my loud laughter. =)

  2. robin says:

    Nice article to explain your methods — informative!

  3. Alex Calò says:

    Thanks for sharing Tim, soundscape recording’s is one of my favourite passions, especially the sea that has a very broad spectrum.

  4. Thierry says:

    Hi Tim, if you want to get even more rejection, then a future experiment might be a Shoeps superCMIT. I tested one recently and although I didn’t have time to use it in a lot of different situations, it was clear that there is a future for the thinking behind that mic.

    Cheers,
    Thierry

  5. Pingback: Noise Jockey » Blog Archive » Recording Single Waves

  6. Frank G says:

    Awesome! I was looking for sound characteristic of the mkh 70 and this was a great read.thanks buddy!

  7. morgan williams says:

    Thank you Tim,plenty to inspire me here.Good luck with your work.Morgan

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