A Little known fact is that Music that is written for Top 40 radio is DESIGNED to have the DJ talk over it.
If you watch the VU meter, you'll see that the beginning of the song is at about -5dB to -10dB. Finishing your Voice Link as the lyrics begin is known as "hitting the post" (most radio automation systems provide a countdown of the intro length, but some DJs do it by sound), and it's an integral part of properly producing a flowing show.
You'll also see that about 20 seconds before the song ends, during the outro, the VU levels drop as well. Same thing. It's designed for the DJ to hit a sounder (St. Ita's Hospital Radio 89.5 fm!), open the mic, deliver his Link, start the next song, and Hit The Post.
Back in the 1980's it was though that the rational for this was to interrupt the recording with voice or jingles or fade-out, so that people cannot illegally record from the radio .
Top 40 Radio isn't designed for you to hear the full song beginning to end with every nuance. It's designed to be a produced, flowing creation of its own, with no fades to zero or gaps.
Meaning of 'Hitting the Post'
Radio DJs seem to be able to smoothly introduce a song, speaking all the way through the song's introduction and then finishing just as the lyrics begin. They even seem to follow the flow of the instrumentals' beats and cadence.
Hitting the post has always required practice and talent because it's all about timing and having a feel for the song. Still, DJs have always had some help.
Hitting the Modern-Day Post
While DJs have always had a little help, making hitting the post sound good requires practice, timing, and even somewhat of a "third sense." Think about it this way. When you're driving a car in traffic and you have to apply the brakes, you develop a feel for slowing down at a consistent pace over time so that you can stop just behind the car in front of you without hitting it. That's the kind of timing, or feel, DJs develop when it comes to talking over the music intros up to the exact point vocals begin.
These days, technology helps even more. With voice tracking, DJs can record what they want to say and physically place that recorded sound bite between songs. Today, voice tracking can make even a less-experienced DJ sound perfect. Still, the old-school DJs who learned how to hit the post have developed a sense of timing and rhythm that elevates their talent and the listener's experience.
Practice Makes Perfect
If you dont know how long the intro is you will need to play it on preFader/cue , listen to it on your monitor or headphones and take a note of what time the vocals kick in. . Most studio equiptment has a timer built in.
Taking the example above of the song with the ten second intro up to the vocals (:10/3:42/fade), if you wanted to Hit The Post this is how you could do it . You know you have 10 seconds of Into Music to talk over before the vocals start on the track,. On average we speak at 3 words per second, so to HIt The Post (Speak up to the Vocals( all you have to do is create a link with with appoximately 30 words. (3x10). 3 (words per second) multiplied x 10 (seconds until the vocals start)
Try it , If it doesnt work properly a slight adjustment may be needed but that is the basics theory behind the practice of Hitting The Post