weird noise

Question
QUESTION: hello. we have a male res and he is very friendly and calm. two nights a go we heard a noise that sounded like a psst, like someone was whispering trying to get someone's attention subtly. we were freaking out thinking someone was outside our appt. we only heard it once. today we heard it again and discovered it was coming from our male res. he pulls his head in, opens his mouth and pssts. its very weird. he has a good appetite, very active, eyes and nose clear, no bubbles or anything. temps are normal, 80ish in and 85ish out. water is clear and clean due to filter. heater and heating lamps as well. 100 watt day and 100 watt UV. doesn't do it often, maybe once every couple of days. is this a cause for concern?

ANSWER: It's not "weird" at all. It's very telling...BUT...you will have to follow THE INSTRUCTIONS as my rules indicate and provide all information as directed or I will REJECT your question.

---------- FOLLOW-UP ----------

QUESTION: species- red eared slider turtle
habitat size- 30 gallon glass
substrate- none
humidity%- no idea
bask/ambient temps- water temp- 85-90 in water, close to 95 on basking area as directed by a vet
lighting: wattage- 100 watt day light and 100 watt UV by exoterra
brand, and type of UVB(tube, coil, spot/flood)- coil
vet history- none I am aware of only had for 1 month
all food offered- reptomin food pellets, plain cooked chicken, occasional strawberries, apples, corn, shrimp, blood worms, live aquatic plants such as hornwort.  
feeding schedule- once every other day
supplements and schedule- reptical powder- once a week
last time ate- Saturday, may 31st at 630 pm
when and how water is given- small bowl on basking area once a day
when last defecated- Friday may 30ith afternoonish
captive bred or wild caught- captive bred
shed recently- every day
other animals living in same terrarium?- yes, female red eared slider turtle

can you help me now???

Answer
Yes, assuming you drop the attitude??? I have directions for a reason. Lack of following them wastes my time and the animal's time.

Is your water temp monitored by thermometer?
You state you have a 100watt Exoterra UV lamp, but them you state you have a compact. No compact is 100watt, so can you clarify?
No vet history, but have you consulted with one, since you state basking area is as directed by a vet?

These symptoms are indicative of a respiratory illness, either infectious or non-infectious husbandry related origin.

The turtle should be isolated from the female into a dry dock condition with basking spot available, basking area temp of 100F and a cool side of approx 86F, and allowed only part time access to deep water once per day for 30min to no more than 2hrs. The existing tank should be emptied and cleaned with boiling water and/or vinegar and rinsed well, including any tank decor and accessories and filter systems, and changing of filter media. If you are not using a biologically active filter, I would recommend one, rated at 1.5 to 2x gph capacity of the tank being used to house the turtles.  

If the turtle's symptoms do not abate within a few days, the respiratory issue is likely infectious in nature, which will not self abate and will likely be fatal without a trip to a veterinarian and systemic treatment with a bactericidal.

Also, a 30 gallon tank is woefully inadequate for 2 Red Eared Sliders, unless these are hatchlings or yearlings at most.