Thunderstone

This small, sparkling stone emits a bright light and loud bang when shattered. 

Source Core Rulebook

You can throw this stone as a ranged attack with a range increment of 20 feet. When it strikes a hard surface (or is struck hard), it creates a deafening bang that is treated as a sonic attack. Each creature within a 10-foot-radius spread must make a DC 15 Fortitude save or be deafened for 1 hour. A deafened creature, in addition to the obvious effects, takes a -4 penalty on initiative and has a 20% chance to miscast and lose any spell with a verbal component that it tries to cast.

Since you don’t need to hit a specific target, you can simply aim at a particular 5-foot square. Treat the target square as AC 5.

Alchemical Power Components

Source Adventurer’s Armory 

While they are effective enough on their own, thunderstones have useful interactions with some spells.

• alarm (M): If cast as a mental alarm, you may have the spell activate a mental and audible alarm. If cast as an audible alarm, the alarm is as loud as a thunderstone and affects creatures in a 10-foot-radius spread as if a thunderstone had detonated there.
• glyph of warding (M): Creatures that fail their saves against a blast glyph are also deafened as if by a thunderstone.

An alchemical power component is an alchemical item used as a material component or focus for a spell in order to alter or augment the spell’s normal effects. What follows is a sample of these effects using this item as a component; your GM may allow other combinations. 

• _{Spells followed by an (M) expend the alchemical item as a material component;}
• _{Spells followed by an (F) use the item as a focus and do not expend it.}

In both cases, the alchemical item does not have its normal effect and does not affect any other parameters of the spell. You cannot use the same item as both a focus and a material component at the same time.