Multiple sensors with individual “roll call” security

I may be starting out here with an ambitious project, but the basic goal is to have several sensors, mostly PIR running off a Mega 2650 and sensor shield. Each sensor monitoring a room, hall, or other location. I want to give each sensor, (whatever type it is) an identity, so that when triggered it then calls on an individual output. Sometimes PIR might be replaced with other sensors to suit the situation. In basic form the outputs might light up individual LEDs, or buzzer sounds. Just to complicate it I thought it would be great to address some sort of media player containing multiple sound files so that a particular sensor addresses its corresponding sound. With pre recorded sound files the user is verbally told the name of the location where a sensor has activated. Thus you can then audibly monitor movements through a building. I foresee that this could supplement CCTV to save security staff the fatigue of watching blank screens and focus attention in the right locations at the right time.

I imagine that this same logic might be applied to say a home built pinball machine where switches and sensors that are triggered could play selected tunes, or initiate displays.

My big obstacle is that I’m new to Arduino and struggling with trying to understand the sketches to drive what I want to do. I assume you put in statements to identify each sensor, what it is and what it is connected to. Would the outputs then have to go to another arduino to address the correct sound? Would you call up wav files on an SD card reader? With multiple ideas I would like to see what unnecessary complications could be simplied.
Ideally outputting the sound into some sort of network stream would allow any PCs or mobile devices on the WiFi to receive the alerts.

I would like to also eventually embed a test program as a software switch parallel to all sensors. The idea is to reserve one input as “test”. Press the test button to send a single logic high sequentially onto each sensor line, thus to trigger each sound file. Just to isolate hardware from software issues.

Presume would need some sort of adjustable delay statement to suit the location whether it be an occupied area or one that is just passed through. In considering this issue I want to ask if a variable logic delay is possible? My thought is to use a variable potentiometer or similar to make “on the go” modifications to the delay time and reduce repeated alerts being unnecessarily sent. Could the resistance value of the POT be read, then converted to a digital value, then each value in array equals pre chosen delays ranging from immediate to infinity. Thus you can quickly disable false positives in a room that is occupied constantly, has pets roaming or other such real life issues.

I’m just looking for directions here on where to read to try and put all of this together. I am also very interested to learn those in the know whether the above is achievable.
Any feedback would be very much appreciated.

DFPlayer Mini is easy to use and cheap. Connect it to a serial port on the Mega, plug in a micro-sd card with many sound files in MP3 or several other formats. It can drive a small speaker directly (e.g. 8ohm 1W) which can be quite loud, or attach to a more powerful amp and speaker.
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I think you need to play with a few ide examples - if your sensors are connected to different digital pins then your sketch , in reading each input ,will inherently know which one it read .
Ie read input A ; input low, thereofr sensor connected to A hadn’t tripped .

Your project is feasible , but I expect you need to study digital inputs and outputs -?there are examples in the IDE

Thank you for you reply.
Will get a DF player as suggested.
As hinted at prior the hardest part for me will be finding the right sketch to achieve end goal.
Any reference to examples appreciated
It is all bit overwhelming but - Time to start the learning curve!

finding the right sketch to achieve end goal.

This is something a many beginners seem to believe. But you won't. When you come up with a new and original idea for a project, that idea will have many similarities with other projects that others have done, but it won't be exactly the same as any of them. Your sketch likewise. You can use other sketches as examples and inspiration, and you can even copy parts of them into your own sketch. But you can't just copy blocks of code from different sketches and dump them together in a single sketch and expect it to work. Integration is much more complex than connecting components. You need to fundamentally understand every line of code, and adjust most of them.

So don't waste ages looking for the mythical perfect sketch. Spend that time working on your idea in more and more detail, and writing it down in English language, and possibly some maths language where appropriate..

Agree , you will get a lot of frustration looking for , downloading and trying to use such sketches .
You are better off building on examples provided with libraries.
If you must download stuff - understand how it works before you use it , or you will learn nothing .
Take little steps and enjoy it