Sami asked:

Why does the Japanese dialogue track sometimes leak to music & SFX track used for dubs? I've noticed this issue in many dubs of older anime. Also many of the ME Tracks have this weird "ghosting effect" in which the sounds that are about two seconds away from appearing in the soundtrack can be heard very silently a second beforehand (this can be noticed in the ends of silent scenes in many older anime).

Virtually all anime (and most other film and TV) audio recorded prior to the 90s were recorded on analog "reel-to-reel" tape. This sort of tape works very similar to how audio cassettes work: a magnetic head records an electrical signal -- the audio waveform -- onto magnetic oxide-coated tape, and the rest of the machine is a contraption to move the tape over the head reliably at a precise speed. Cassettes use a very thin magnetic head to record four channels of audio -- two track stereo in each direction -- across the width of the tape. The tape travels at 1 & 7/8ths inches per second, and is 0.15 inches wide (about 1/8th of an inch).

Professional reel-to-reel tapes are pretty much the same thing, except the bare reels are stored without an external shell and take-up reel. The tape goes much faster -- usually 15 inches per second, but sometimes 30! Additionally, the tape head is much wider. All this extra speed and head width allows for a much more robust signal to be recorded on the magnetic coating on the tape, resulting in FAR better audio quality. With the right equipment, tape recorded this way can still rival the best professional digital recordings today. Stereo and some mono recorders use tape that's 1/4" wide. This format was also popular with higher end music consumers back in the 1970s, but isn't used much today.

For television and video production, that standard 1/4" tape was used for recording individual elements, like sound effects, voices, and location audio. However, when it came time to edit all of the sound together and synchronize all of it to picture, a much wider tape was used. Reel-to-reel recorders with eight, sixteen, 24 and even 32 tracks were built. And since these machines were made for professional audio work, manufacturers didn't want to use smaller tape heads and thinner tracks recorded onto the tape, as doing so would lower the quality of an analog recording. Instead, they made the tape WIDER.

Audio tape as wide as two full inches was a common sight in any production facility that did multi-track audio recording and mixing. These tapes were quite heavy -- they came on big metal reels, and cost as much as US$200 (for 3600 feet, which was only 48 minutes at 15 IPS, or 24 minutes at 30 IPS), and the machines that could record onto them could cost well over US$100,000. And this is back in the 70s and 80s! Adjusted for inflation, they'd be well over the quarter million dollar range today.

Analog recording sounded wonderful and warm, and many music and audio otaku obsess over original studio recordings made on some of this equipment today. Anime was typically not given such luxurious treatment -- tape was likely recorded at slower speeds and with only 8 or 16 tracks. Nonetheless, all anime audio elements prior to digital were recorded and stored like this.

Magnetic analog audio tape has a lot of problems. The first problem, as you describe, is called "bleed through." This is a phenomenon where a machine playing back a tape has heads that are slightly misaligned with the machine that recorded the tape, and therefore, the heads are picking up a little bit of the audio from neighboring tracks. So, let's say you have a master where channels 1 & 2 are dialogue, channels 3 & 4 are sound effects, and channels 5 & 6 are music.. You might be trying to play back just channels 3-6 so that "music and effects" can be provided to an overseas company for dubbing. But the tape head for channel 3 is picking up a little bit of stray audio from channel 2 next to it, and therefore a faint, ghostly rumble of dialogue can be heard.

Another common problem is tape stretch. Magnetic tape is literally just finely ground magnet-sensitive particles stuck to a thin layer of plastic. That plastic can stretch over time. This can cause all sorts of problems: audio that loses sync with video, and audible changes in pitch ("wow" and "flutter"). Worse, some older tape had adhesive that loses its bond with the magnetic coating over time, causing it to fall off and destroying the recording. Many studios sitting on piles of old tape have been forced to literally bake the tapes in an oven at a low temperature to temporarily reset the glue, before digitizing their contents for safe keeping.

Also, tape was stored in tightly wound reels, and it wasn't uncommon for the tape to "transfer" its magnetic signal onto the layer below it -- which would come just a few seconds later when the tape was played back. This resulted in an odd "echo" effect, where whatever came before is faintly repeated just a few seconds later.

Analog fetishists might pine for the old days, when tape was king and nobody used computers to capture audio and video. However, most of these people have no idea what a nightmare tape could really be. We're very lucky to live in an era of cheap hard drives and burnable discs. Digital storage isn't always reliable in the long term, but it sure is a lot better than tape was.

Thank you for reading Answerman!

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