senken
to lower
To actively move something downward or bring it into a lower position.
Er senkte seinen Blick, als er angesprochen wurde.
He lowered his gaze when he was spoken to.

to lower
Loading your saved state.
to lower
To actively move something downward or bring it into a lower position.
Er senkte seinen Blick, als er angesprochen wurde.
He lowered his gaze when he was spoken to.

'Senken' (to lower) is a transitive verb. This means it always needs an accusative object—that is, someone or something that is actively being lowered.
Die Firma muss die Kosten senken, um wettbewerbsfähig zu bleiben.
The company has to reduce costs in order to remain competitive.
In the meaning 'nach unten bewegen' (to move downward), 'senken' (to lower) is often used with body parts or the voice. Typical phrases are 'den Kopf senken' (to lower one's head), 'den Blick senken' (to lower one's gaze), or 'die Stimme senken' (to lower one's voice).
Als sie die schlechte Nachricht hörte, senkte sie den Kopf.
When she heard the bad news, she lowered her head.
In the meaning 'reduzieren' (to reduce), 'senken' (to lower/reduce) is used very often in economic or scientific contexts. You can 'senken' prices, costs, taxes, interest rates, or even a fever.
Der Supermarkt hat die Preise für viele Produkte gesenkt.
The supermarket reduced the prices of many products.
When something goes downward by itself, the reflexive form 'sich senken' (to descend/sink) is used. This is often the case with natural phenomena, such as 'der Nebel' (the fog), 'die Nacht' (the night), or 'die Dunkelheit' (the darkness).
Die Nacht senkte sich über die Stadt.
Night descended over the city.
to fall
'fallen' and 'senken' can both express that a value, level, or amount becomes lower. The difference is often whether something happens by itself or whether someone actively does something. 'Die Preise fallen' means: prices are getting lower. In 'Die Firma senkt die Preise', the company is acting actively. With 'sich senken', 'senken' can also be used in a way similar to 'fallen', for example 'der Wasserspiegel senkt sich' (the water level is dropping). In everyday language, 'fallen' is very natural with numbers, prices, and temperatures when no acting person is important. 'senken' fits better when someone deliberately reduces something.

Die Firma senkt die Preise, weil weniger Kunden kommen.
The company is lowering its prices because fewer customers are coming.
Nach dem Sommer fallen die Temperaturen langsam.
After summer, temperatures slowly fall.