Maybe. It is difficult to answer this question without knowing exactly what model of TV and what kind of external speakers you are talking about. In general, if you are using your TV to watch "over the air" HDTV (in other words, not cable or satellite) or if you have a "smart" TV, you need a way to get the audio from your TV to your external speakers. The best way to do that is with an optical cable.
I have two TVs in my house that are hooked up to external speakers with an audio cable and both set-ups required the use of an optical cable to get the audio from the TV to be played through the external speakers. Check the back of your TV and external speakers for an optical audio port. In my first set-up, I have a Sony TV hooked up to a Denon receiver that powers a 5.1 speaker set-up. This is an older model TV and for years I used it with DirecTV, which was hooked up to my receiver via HDMI, so I never noticed that I "needed" an optical audio cable. However, last year I cancelled my DirecTV and couldn't get the audio from my TV's tuner to come out my home theater speakers, until I purchased an optical cable (Insignia). I plugged the optical out on my TV to the optical in on my receiver. I pushed a button on my receiver telling it that the TV was hooked up via optical input. The next thing I knew I was listening to amazing sound quality using an antenna. It's nice.
In my other set-up, I have a Sony Smart TV hooked up to a Sony Sound Bar (external speakers). In this set-up, I had to use an optical cable by hooking up the audio out on the TV to the audio in on the soundbar. However, my soundbar came with an optical cable, so I did not have to purchase one.
I know that I have different equipment than you asked about, however, I believe most manufactures have similar audio and video ports and set-ups. I hope this helps answer your question.
Insignia™ - 6' Digital Optical Audio Cable - Black
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